Energy Efficient Custom Homes11/12/2022
Custom Home Build- Decking
Decking is a widespread, popular feature of Australian custom homes. Since outdoor structures must be constructed from materials suitable for exposure to the elements, decking frames are most commonly made of H3 treated pine which is suitable for exterior above-ground use. For the in-ground parts, we have to use concrete, steel or durable timber species, such as cyprus, red gum, merbau or H4 treated pine. In high bushfire areas (BAL29 and above) we have to fully enclose the treated-pine frame (gaps up to 3mm are permitted) or use a bushfire resistant species of timber or steel.
The decking boards themselves can be made from a wide range of timber species, the cheapest is H3 treated pine; probably most widespread is merbau which comes in widths of 70mm, 90mm and 140mm; spotted gum is also popular; blackbutt and ironbark are less common, mainly due to limited availability and associated price. We have also used laminated bamboo, which was easy to lay and has performed quite well over the ten-year period since installation. Recently, various deckings made of recycled plastic have come on the market. These have gained some popularity due to their superior visual appearance and no need for oiling or other maintenance. The main draw back in these products is the huge expansion rate that comes with temperature changes, and so the boards need to be laid in a specific way to eliminate huge gaps between the boards. The other drawback is that nobody knows how they will look fifteen years from now, and an already recycled plastic product may be hard to recycle again.
Decking boards can be fixed to the supporting frame in different ways. In use are specially designed dome-head nails made either from galvanised steel or stainless steel, but probably the best option is to fix the decking directly down with stainless-steel screws. There are a few self-drilling products on the market, but nothing beats a pedantic carpenter carefully predrilling the hole in the boards for every single screw. The other option is to screw the decking from the side with specially designed screws or use grooved decking boards and fix it down with specially designed brackets.
Custom Home Build – Excavations
Most custom new build homes, custom home extensions, and custom landscaping will involve some sort of excavation. It may be just small footings for decking, potentially dug by hand, or a large site cut in rocky terrain on sloping land which would involve large excavators and several trucks with trailers for disposal of the excavated material.
It’s crucial to get as much information as possible about the terrain before excavation starts. For custom new builds in extensions, a building permit will require a geotechnical report—in building jargon known as a ‘soil test’. This gives the custom house builder a good idea about what they’re dealing with deep underground. Valuable information can also be obtained from the Dial Before You Dig service. Some information can also be gotten from a ‘land slip assessment’, a specialised geotechnical report required on most steep sites within the Yarra Ranges Council.
The local water authority will also have very reliable and accurate diagrams about underground sewer lines which are very valuable to have during footing excavations for home extensions. In my extensive experience of custom home extension buildings, I hardly remember any project where we didn’t encounter any sewer or storm-water pipe which must then be promptly diverted. When negotiating with a custom home builder about a proposed custom home extension, make sure that potential damage of underground services is included in the total contract price and that the custom home builder has the resources to fix it promptly if an accident happens. There are no records or diagrams for most storm-water pipes in most backyards, and damage of the pipes is, in most cases, inevitable and must to be dealt with before the next rain to avoid excessive site saturation with storm water.
With large site cuts it’s very difficult to estimate the exact amount of soil to be taken away and the costs associated. However, any reputable custom home builder should give you a fixed price for the whole project, regardless of uncertainty. Most unexpected costs arise from contaminated soils. We’ve discovered many nasty surprises buried in backyards, including asbestos. Luckily, no dead bodies, so far …
Large amount of clean fill such as clay without top soil can be in many cases be disposed of without a dumping fee at different sites all around Melbourne where they are needed for site stabilisation, levelling and similar. Most good excavation businesses will also have established contacts for soil disposal. There is also a Facebook group where you can post your request for soil needed or soil to be disposed of.
Custom Home Build – Concreting
Concrete is one of the most wide-spread materials used in the construction industry. Custom home owners will generally engage concreters for new driveways, landings, steps, cross overs, paths and house slabs—in the case of owner builders.
Concreters range from small one-man bands suitable for very small jobs, to very skilled large teams who normally deal with house slabs or similar larger projects. Concrete as a building material allows for many different finishes such as:
Plain grey concrete – this is the most basic form of concrete and is usually smooth trowelled in case of house slabs or rough trowelled in case of driveways, walkways and similar. It should be laid on a bed of crushed rock and reinforced with steel for larger areas to minimise cracking.
Coloured concrete – this is used for driveways, walkways and similar. It should be laid on a bed of crushed rock and be reinforced to minimise cracking. Coloured concrete has an oxide pigment mixed into the concrete mix and should be sealed with concrete sealer to enhance the colour. The sealer does fade away after a few years and should be reapplied to keep the original shiny appearance.
Exposed aggregate concrete – This is one of the most complex to install and requires a concreter with good skill to get the desirable outcome. Custom home owner chooses their desired mix of texture and colour from what is available at the nearest concrete plant where they provide exposed aggregate concrete (check https://mentonepremix.com.au/) After the concrete has been laid to the desired area and height, it gets sprayed with a chemical which prevents of the upper layer of the concrete hardening. The next day the concrete is washed off with a high-pressure water jet to expose the beautiful structure. Exposed aggregate concrete should get sealed immediately after being washed.
Burnished concrete – This is normally plain-grey concrete trowelled to high smoothness with mechanical trowels (helicopters) some helicopters have Teflon blades to achieve an extreme level of smoothness. Burnished concrete is most common in large commercial projects (most Bunnings stores have burnished concrete floors). However, recently it has become popular in domestic applications as a more cost-effective alternative to polished concrete.
Polished concrete – This is one of the most complex kinds of concerete to install and finish. It may be just plain-grey concrete or any possible colour mix, and when laid it can be sprayed with pebbles or any type of small rocks of different colours and shapes. It’s very difficult to achieve consistency, and so the concreter should educate the custom home owner about the expected imperfections in the final product. The polishing process itself can be done just with rough grinding and sealing the surface with polyurethane sealant. However, that’s the cheap way, and the concrete sealer will become yellowish in colour as time passes. The best way is to get a very smooth finish, which doesn’t require any sealant and will provide a lifelong finish to the floor. Concreters acieve this level of smoothess by using mechanical ‘helicopers’ with teflon blades, fast spinning them over concrete a few hours after it’s laid. You can see this kind of finshes in warehouses such as Bunnings or similar. Polished concrete around swimming pools should be acid etched to avoid them being slippery.
Despite concrete’s widespread use, due to its durability and practicality, there are a few drawbacks. First, the production of concrete is an extremely high-carbon emission process. Second, on the more aesthetic side, there are two types of concrete: the concrete which has cracked, and the concrete which will crack. Cracking of concrete by itself isn’t a defect if it’s within the tolerances described in the Guide to Standards and Tolerances, and there are different ways to minimise cracking. The most common and obvious is to install steel reinforcement in the concrete; the other is to make control joints at the weak points—they can be cut in cured concrete or trowelled in during the concrete pour.
Custom Home Build – Brickwork
Brickwork is normally part of larger custom house building projects. However, a custom home owner may engage only bricklayers for various projects.
One of most common independent bricklaying projects is building a front fence. With this project, you should pay a lot of attention to what is allowed under your local council regulation and be sure to establish the exact line of your front boundary. If the front boundary isn’t yet exactly determined, it’s best to engage a licensed land surveyor.
Before brickwork on the front boundary starts, custom home owners will need foundations with an appropriate depth and width of footing plus associated steel reinforcement. Attention needs to be paid during the excavation of the front footing to not damage the existing services which run underground to your property. Telecommunication services can be quite shallow. Gas and electrical services should be a minimum of 600mm deep, but don’t take my word for it; sometimes they run shallower. Water supply may be at any depth.
Before any digging, custom home owners should get all available information on Dial Before You Dig at https://www.1100.com.au/ However, not all information is there, and sometimes, before the excavator can be engaged, careful hand excavation is needed until all services are located.
Sometimes all that’s required is to patch up existing damaged brickwork or alter it as desired. It’s quite an art to get old brickwork patched up without the patch being noticeable. First you need to source the matching bricks. Depending of the age of the existing brickwork, the best way is usually to visit the nearest new brick supplier. We mostly use Melbourne Bricks. They have an expert who comes on site to asses existing brickwork and suggest the closest match. The other option is to visit brick recycling companies. We use Beaver Bricks; they have a wide range of old bricks and, with a bit of luck, you can find a perfect match.
The other important visual element in brickwork is mortar. Mortar can be done different ways: finished flush with the face of the bricks or rolled in. In older projects it was recessed about 10mm inside the face of the brickwork. The trickiest of all is to match the mortar colour as colour depends mainly of the type of sand used in the original mix, as well as the type of cement. Also colour changes as the mortar dries, so what may seems like a perfectly matching mix, may look quite different a few days later.
A good bricklayer should inform you about the possible imperfections, and there is no guarantee of a 100% perfect match, however skilled the bricklayer, but a bit of luck can lead to repairs that looks near perfect and impossible to spot for the average observer.
Custom Home Build – Landscaping
Good landscaping can make a massive difference in the appearance of the custom designed home. Landscaping is mainly about surfaces and plants around the buildings; however it can get quite complex and intricate when large rocks are introduced, sometimes around swimming pools or ponds with potential streams of water and incorporated on decking with irregular shapes on different elevations. Landscapers also deal with retaining walls.
Good landscapers are quite hard to find and usually very busy.
Custom Home Build – Pergolas
Pergolas are considered any outdoor any areas covered with a roof and attached to the house. If the structure is not attached to the house, we call it a gazebo.
We do need building permits for covered pergolas. Only unroofed pergolas with an area of less than twenty-square metres are exempt.
There are many different types of pergolas, from simple structures covered with polycarbonate roof sheets to very sophisticated structures with ceilings, integrated downlights, ceiling fans and even in-ceiling built-in speakers. Accordingly, the price can vary dramatically.
All roofed pergolas must have their own gutters with connections to a legal point of discharge on your property. Only qualified and registered roof plumbers can install metal or polycarbonate roof sheets on a pergola with all its associated guttering and downpipes.
In regards to Victorian regulations, it’s legal for anyone to lay a tiled roof on any appropriate framed structure. There is no legal requirement for any kind of licensing or work experience. It is, however, an offence if anyone not registered with the Victorian Building Authority installs a metal sheet roof or even polycarbonate roof sheet.
Custom Home Build – Bathroom or Laundry Renovation
Bathroom and laundries are wet areas of the house, and water has a very destructive and damaging force on buildings. Even when bathrooms are a quality build and well maintained, we expect them to be in need of renovation in about twenty years.
There are no shortcuts when dealing with bathrooms and laundries. The only real way to do it, is to strip everything out of the room, including plaster or at least most of the plaster, and carefully assess any potential water damage on timber framing. Special attention is to be paid to the floor and junctions between the wall and floor.
When the bathroom is cleared of all old fixtures, tiles and plaster, the plumber can run new piping, including hot and cold water and waste-water pipes. At this point, to make sure the connections are in the right spot, it’s important that the plumber knows the exact type of toilet you will use as well as shower mixer, shower rail and vanity taps.
If a wall-hung vanity unit is required, the carpenter will have to consider this and install enough hard-fixing points in the wall to deal with the weight of the vanity unit. The same consideration must be done if you plan to hang a washing machine or dryer on the wall of the laundry. Placement of toilet-roll holders and towel holders will also need to be considered at this point.
After the plumber, an electrician can install provisions for the proposed power points, lights, exhaust fans, heated towel rails and automated toilets—if you plan to install one. Careful planning consideration is needed for power points around vanity units, as they can’t be closer than 150mm from the edge of vanity bowl or need to be 400mm above. In small and constrained bathrooms, this could be quite an issue, and a lot of careful planning is needed to achieve compliance with regulations.
When all installations are in place, there is need for plastering. Only a water-resistant and approved plasterboard or fibro-cement product can be used for lining bathroom walls, and floors need to be made either of 20mm compressed-fibro-cement sheets or lined with 6mm fibre-cement sheet over structural timber flooring. If a tiled shower base is proposed, there has to be provision for structurally sound cement screeding, which should be not thinner than 20mm or, alternatively, an off-the-shelf, ready-made shower bed can be installed.
The waterproofing happens after all the floor and wall lining has been installed. This is the single most often misunderstood step and point of many failures. Australian Standards AS3740 deals with bathroom waterproofing and should be strictly followed, including manufacturer installation instructions.
After the waterproofing is installed and cured as per manufacturer instructions, it’s time for tilers. They usually start with the tiled shower bed (if there is one) and work all the floors before starting the walls. When all the tiles are laid, they apply grout between them. However, there should be no grout on the wall-floor junction or wall-wall junctions. These junctions should have flexible, sanitary-grade, coloured silicone sealant to allow for expansion of different surfaces and minimise water penetration between the tiles.
When the tiles are done, the carpenters or cabinetmakers can install the vanity units, and the plumber can install the toilet, taps and bowls. This is also the time for the electrician to fit all power points and switches. Then the glazier installs the shower screens and mirrors and a corker seals all the gaps.
Custom Home Build – Structural Modifications
Our way of life is constantly changing, and as our lifestyle changes so do our needs for living spaces. Forty or fifty years ago it was normal to use one room for cooking and eating our meals and another room for family gatherings and watching TV. Today we prefer these two rooms joined in what we call open-plan living.
To achieve open-plan living in old houses, we need to remove a wall or a few walls to create a large open area. This inevitably changes the house’s structural integrity and the way it was designed. Clients often refer to ‘load-bearing walls’ or ‘structural walls’, but the truth is that even if a particular wall doesn’t support the load above it, it’s still part of the existing house structure that acts as brace for racking forces. Racking forces are forces acting on a house in a horizontal way, such as wind and earthquakes.
A good custom home builder should be able to determine what is needed for a particular structural modification. However, custom home builders will need a structural engineer to specify beams, bracing and connections for any wall removal. Transferring a load from a wall to a beam will create additional forces on each side of the beam, and this will, in most cases, need additional support on either side and sometimes footing reinforcement. It may be relatively easy to provide additional footing support if the house is built on stumps. Usually this is done by opening the floor and excavating an additional footing under the house. If the house is on a concrete slab and the engineer specifies footing reinforcement, it’s a much bigger and more complex job to provide the desired support for the beam.
Beams can be steel or timber. Timber beams can be solid timber or glue-laminated timber or LVL which stands for laminated veneer lumber. LVL is very popular due to a wide range of availability in sizes and lengths, and exact engineering tables specifying load-bearing ability. In most cases they also have some degree of termite protection.
It may seem simple to remove a wall or a few walls and replace them with beams, but much more is involved. Almost all walls have live electrical wires running through them and sometimes water and gas pipes, which need to be dealt with. In the ceiling above the walls, we will find evaporative cooling ducts and ducted heating ducts, ducted heating heaters with associated gas pipes and electrical supply, and old gravity-feed water heaters—which most often have been disconnected decades ago, but nobody took them out of the roof space. And, yes, we do find many dead possums and rats.
Most structural modifications will need a building permit.
Custom Home Build – Extensions
When there is not enough room in the house due to an additional family member or other circumstances, we first try to see if the family’s needs can be meet by simply rearranging internal spaces; for example, to divide one large bedroom into two small ones. In most cases, however, that’s rarely an option, and we need to increase the external perimeter of the house. If that’s also not possible due to lack of available room on the land, then, as the last and most expensive resort, we add a second storey on top of the existing house.
Home Extensions are very complex custom building projects, and the price per square metre will almost always be much higher than for a brand-new custom home. The large price hardly ever comes from the cost of any single item in this kind of construction, rather the final figure is usually composed out of hundreds of small items and steps. However, a costly roof line could, potentially, be avoided. Incorporating the existing roof line over the new extension usually means a lot of work on the existing roof as well as on the new roof. When the client is on a tight budget, we suggest giving the home extension a flat roof; that minimises the work on the existing roof and speeds up the process.
When designing an extension, we are, most often, aiming for the same appearance as the existing building. However, sometimes custom designers intentionally add a contemporary-looking addition to an old-fashioned house, and if designed properly, it can look very good.
When building an extension, there is almost always also some work to be done on the existing house. Setting the floor level of the proposed addition requires careful consideration, as do the floor coverings, to ensure a smooth and seamless transition from the old to the new part of the extended house. During the construction, there will, almost always, be some interruptions of the existing underground or overhead services, so careful consideration, planning and research is needed to locate the existing services and decide how to deal with them.
Even the best custom home design and designer can’t predict everything needed in one extension. When works starts, we often encounter surprises, but a good, experienced custom home builder should be able to make allowances for most of the possible scenarios.
Volume builders are normally found in outer suburbs on new land developments. Generally, they’ll have their show houses near large developments, and they can be an extremely cost efficient way to get a new home. They will have their home designs ready with all associated pricing and inclusions, and often they’ll offer land and home packages with very low deposits.
Due to the volume of their turnover, they’re able to obtain very good prices from their suppliers and subcontractors. Fixed designs also means that their standard homes can be built without intensive supervision, and one site manager can manage ten or more building sites simultaneously, making the process more cost efficient.
Volume builders also know exactly, with great precision, how much of each material will go into individual homes, making them able to work on a very slim margin. Unfortunately, slim margins and great competition between volume builders means that they quite often fail and go bankrupt, leaving numerus clients out of pocket and making newspapers headlines.
The other downside of volume builders is that they’re quite inflexible with changes of their set designs. All their subcontractors are very familiar with the design, and any change must be documented, and plans changed and forwarded to site supervisors and subcontractors. All this makes any change a costly exercise.
Volume builders are a good and cost-efficient way for first home owners to get their first home. The downside is that they most often operate in outer suburbs that don’t have very well-developed infrastructure such as schools, hospitals and jobs.
Custom Home Build – Custom New Homes
A lot of effort goes into each custom home. Architects and designers work with clients to produce beautiful plans, which remain just that—plans—if the custom home builder isn’t involved early on.
The custom home builder is the only person in the design-construction project who gets paid only if the construction goes ahead. For that reason, the custom home builder will need to make sure they meet the client’s budget expectation and capabilities. One major cost-related parameter is, obviously, the size, so very early on the size of the proposed building will need to be determined. In most cases clients realise early on that fourteen bedrooms, ten bathrooms, four living areas and an underground basketball court will be a bit over their available budget, so we cut back their dream design to suit more everyday needs.
The level of finishes and inclusions is another cost-related parameter. Surprisingly, we can get quite extravagant-looking finishes which don’t break the budget by using off-the-shelf solutions and products. Prices tend to skyrocket when a lot of custom-made details are specified, as these consume a lot of time from highly skilled/paid trades.
Another factor affecting the budget is the Bush Fire Attack Level, known as the BAL rating. A high bush-fire rating could significantly affect the price. So the bushfire rating of your site should be determined very early on in the design process.
It’s very likely that custom homes will be on sloping sites, and the degree of slope and general accessibility will affect the design-and-construction cost significantly. Difficult excavation due to rocky terrain and the necessity of retaining walls can contribute significantly to the overall cost.
An engineer will need to be consulted soon after the preliminary drawings are completed and confirmed by all parties—architect, builder and owner. Engineers, however, do tend to specify standard solutions, which they just copy and paste into the engineering drawings. Architects are mostly unaware of the cost implications of such copy-and-paste structural design—why would they care when they’ll get paid regardless of whether the construction will ever begin?) Experienced custom home builders should, at this point, suggest/require alternative solutions from the engineer. The most obvious example is the use of core-filled blockwork or core-filled double brickwork as retaining walls. It’s very labour intensive to bring concrete blocks on site, lay them up, reinforce them with steel, then core fill them with structural grout and finally waterproof the finished product. Much faster and more cost efficient is to use core-filled PVC panels, which are much faster to install, cheaper and don’t require waterproofing. We use AFS formwork.
For a custom home, it’s a good idea to engage an experienced interior designer. I say experienced because it’s important that suggested finishes aren’t just taken from Pinterest or Instagram, but are exactly what the plans specify, with the supplier and price attached.
It is quite common that local council regulations require a planning permit for a custom home, and this should be determined very early on and the required application lodged with council. Usually no major design work is done during the planning-permit waiting time due to the risk that the council may request a major change that requires a significant overhaul of the existing design. When a planning permit (where needed) is granted, there is no major legal obstacles for the project to go ahead.
The final version of the working and engineering drawings can be completed, and we should already have the BAL report and the geotechnical report (also known as ‘soil test’ in construction jargon). An energy performance assessment will need to be done, and if building on sloping land, a landslip assessment may also be required. We will need a legal point of discharge from the council, and if that’s not available, they’ll request a storm-water-discharge system done by a civil engineer. Surveyors will also ask if the property is serviced by a mains sewer, and if it isn’t, the council sanitary department will specify an on-site septic system which may be an additional and quite-costly item.
Custom Home Build – Concrete slab or stumps?
There is no clear cut answer to the question of whether to build a home on a concrete slab or stumps. It all depends on each particular site and the shape of the proposed building.
Generally, concrete slabs are more suitable for flat land with a consistent soil profile. There is also some thermal performance benefit. Soil at a depth of one metre is around fourteen-degrees Celsius in the middle of a Melbourne winter. If we put a concrete slab on it, this energy helps to warm the house. Two identical houses, one on a slab and one on stumps will have significant difference in thermal performance due to heat from the ground.
The downside of a concrete slab is that it requires a lot of preparation work beforehand. All the underground sewer, storm-water pipes and electrical supply need to be organised before the slab is poured. It’s not uncommon for concreters to break sewer pipes during preparation works, and if this isn’t rectified immediately, it could be a big and very expensive job when the custom house is completed.
A good custom home builder should organise a pipe inspection with a plumbing camera to avoid later problems. All slab penetrations such as pipes should also get treated by a termite specialist to avoid potential infestation. Also needed is great precision in positioning the pipes. It’s extremely difficult if after the concrete is poured, we discover that we have a toilet pipe in the middle of the living room. Concrete slabs are also an extremely carbon intensive structure.
Stumps, on other hand, offer more flexibility in setting different floor levels in the same house. All plumbing can be done at a later date when the frame is already erected and positions exactly determined. The most common stump material is concrete. However, timber stumps are still in use, and they could have a long lifespan if there’s good drainage. We prefer to use electro-galvanised steel posts with additional protective coating, as they’re much easier to handle than concrete stumps and offer a greater lifespan than timber stumps.
Custom Home Build – Multi Units
Many people recognise that it’s posible to make great profit by subdividing their land into multiple smaller lots and building individual units on it. These custom multi-unit projects vary in size from putting a single unit or townhouse on the back of an existing house, up to twelve or more units on a previously single piece of land.
The subdivision process is lengthy and complex. Financial viability often depends on how many units one can build on certain land. Designers have different levels of skill and experience, and it’s well worth talking to different designers to get their opinion about how many units can be built on your land. This can make the difference between making money or making a loss.
A good example of the difference between a good and bad designer is the project at number six Bedford Rd, Ringwood. If you drive past, you’ll see a five-unit development on only 700sqms of land. You see that the side walls are made from bricks, but the front wall is smooth sheet cladding. This is because the standard brick-veneer wall is 240mm wide, whereas a sheet cladded wall is only 110mm wide; this 130mm difference meant that the designer was able to squeeze five units on site instead of four, which make a big financial difference for the owner.
Every subdivision project needs to be approved by council, and they won’t necessarily approve a designer’s opinion. Countless conditions need to be meet before gaining council approval. Every council has its own rules, and every land has different overlays, so even in within the same council, there may be vastly different conditions to meet before final approval is granted.
Council will not only dictate the height and shape of units, but also common services. Plans need to be approved for the driveway, complex storm-water systems and even landscaping with an exact schedule of every plant to be planted and where.
The approval process for simple projects may be resolved in six months or even less, but more often than not we should allow twelve months or more before the custom multi-unit project is ready for construction.
When building three or more units on site, most councils will also require payment of an open-space contribution, which is a kind of council tax on new developments. This is a significant amount of money and should be considered when calculating the financial feasibility of the project.
Custom multi-unit projects attract a lot of custom home builders due to the significant amount of money involved. However, where there is a lot of money, there is a lot of competition, and many custom home builders get into such projects with very small margins and so the rate of bankruptcies within custom multi-unit builders is very high. It can be very painful for an investor to have a custom multi-unit builder go bankrupt in the middle of their project. It will be difficult to get a new custom multi-unit builder to complete the job, and the new builder will charge significantly more than the previous builder. There are many cases where a custom multi-unit builder entered into a new multi-unit contract very cheaply, just to get the job, because he lost money on a previous job and is desperate for some fresh cash flow. However, this cycle can be repeated only two or three times before the custom multi-unit builder is met with reality and finally goes bankrupt.
Investors should be very wary about custom multi-unit builders offering very low prices. If anything seems to be to good to be true, it probably is. More experienced investors are well aware of this, and once when I was in negotiation for an eight-apartment building in Mentone, the owner, an experienced investor with many past projects, told me, ‘I can’t afford a builder who won’t make any profit on my project.’ Very wise words.