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                                                     The Building Envelope

The building envelope is often the most neglected component of your home yet it is by far the most important. In order to maintain its integrity a few but vital questions should be asked followed by respective inspections and finally measures taken to address any deficiencies promptly.

  • Is moisture penetration a problem in your building’s walls, joints or flashing?
  • Are windows and doors leaking air or water?
  • Do you see signs of brick or concrete walls/foundations cracking, staining or deteriorating?
  • Is there excessive condensation on exterior or interior walls and windows?
  • Is mould appearing on walls or carpets?
  • Is the sealant on your wall cladding system discolored or deteriorating?
  • Has your window curtain/wall been examined recently for structural soundness and maintenance concerns?

Your buildings wall system is one of its most important defenses against moisture penetration, heat/AC loss and structural problems. And even a small moisture penetration issue can eventually lead to a larger and more costly condensation, mould or “Sick Building” issue, putting the health and safety of building occupants at risk. At the same time, being proactive on repairing and maintaining your wall system now can save thousands of dollars later—as well as equally costly disruption to occupants.
We can perform a thorough inspection of your building’s exterior façade, including a thermo graphic evaluation of air and heat loss, the use of a moisture meter for water penetration measurement and a fiber optic camera for examination of wall assembly cavities without the need to open large inspection holes in the envelope. Depending on your needs and budget, we can provide a comprehensive design of repair service, including prequalification of sub contracts. Michael Anderson also offers contract administration and inspection services to ensure the work meets your goals, budget and municipal building codes.
Once you decide to repair your leaking prop­erty, it is important to get expert help to plan and undertake repair work properly.
As a homeowner it is also important to undertake routine maintenance, because not doing so can contribute to leaking problems. This can result in a smaller settlement during the dispute resolution process, on the basis that the homeowner contributed to the problem by not maintaining the house properly.
1 Routine house Maintenance
The Building Code sets out the expected lifetimes of the different components of a house, which rely on a certain level of maintenance being undertaken in that time.
There are various things that you can and should do to maintain your house, such as:
• Clearing all gutters, downpipes and balcony drains of blockages so that rainwater can drain away quickly
• Inspecting roofs for areas of eroded roofing material, corded flashing and failed caulking that could allow water ingress.
• Repainting cladding at intervals recommended by the paint and/or cladding manufacturer to maintain an impervious coating• keeping the dirt level in gardens below the bottom edges of cladding to prevent moisture and soaking up inside the cladding. It also prevents the ingress of carpenter ants.
2 Mitigating damage if your house is leaking
If you discover that your home is leaking, it is important to mitigate the damage until permanent repairs can be made.
• If you can find out where the moisture is getting into the house, try to block any leaks temporarily, but don’t rely on a temporary repair for too long.
• Lower the levels of dirt in gardens alongside the house to at least 150 mm below the bottom edge of the cladding to help keep dry the bottom plate timbers in a wall.
• Temporarily seal cracks in monolithic claddings (such as fiber cement (Hardi Plank), stucco or plaster over polystyrene).• Temporarily reseal windows where necessary. Some poorly installed windows rely on silicone sealants to maintain weather tightness, but these sealants deteriorate within a short period of time due to the contraction and expansion of dissimilar materials.
3 Scenarios for repairing a leaky house
Organizing permanent repairs to your house requires careful thought about each step. For example, identifying moisture in the walls and its source, and designing and supervising repairs.
Fixing problems so that they do not recur can involve quite extensive repairs.
There are no general rules on repairs as every house is different. The scope of repairs should reflect the design of your house, as well as the leaking problems. This scope needs to be developed by an experienced building professional, preferably with experience in remedial work for leaky buildings. Repairing the damage could involve some or all of the following work

• Windows - If the windows have been installed incorrectly without flashings, they usually have to be removed and re-installed with the correct flashings, peel and stick, building paper, foam rod insulation and sill tape.
• Cladding - If fiber-cement claddings have been installed without control joints that allow the sheets to move, the cladding often needs to be removed (in part or along entire faces) so that the sheets can be refitted with the appropriate joints in place including underlying flashing.
• Cladding - Replacing decayed framing timber can require the removal of cladding up to 1 m from the boundaries of the decay. Removal of cladding can also result in damage to sheathing and house wrap, and these may have to be replaced.
• Rain Screen - The municipality may require that rain screen be installed along some or all facades as a condition of the building consent for the repair. This will happen if the cladding is a high-risk cladding such as fiber-cement, and the design features of the house are also deemed high risk by the municipality. If a cavity is required and there is not one there already, all existing cladding must be taken off and new cladding installed over furring strips to form the screen.
• Balcony – Guard rails damaged by rot usually have to be demolished and rebuilt. If you have a balcony where you suspect the rails are damaged by water, be aware that rot will have reduced their structural integrity. Avoid the area and get an expert to inspect it.• Decking - If a deck is leaking where it meets the house, the deck’s waterproofing membrane will probably have to be lifted and re-laid. Cladding adjacent to the deck may also have to be replaced to ensure a watertight seal between deck and wall.
The repair work must be done thoroughly and professionally if it is to protect the building in future. Doing the work thoroughly can mean considerable disruption during repairs. Conversely, some repair proposals may be cheaper and less intrusive, but could also be inferior in quality and may ultimately leak again.
4 Organizing an effective Repair Contract
Organizing an effective repair contract requires a ‘scope of works’, which is a full description of what needs to be done. This includes drawings of the important details and a contract with a builder to ensure you get what you are going to pay for. There are four main steps.
1 Specification – To define what has to be done as precisely as possible, using as many drawings as is considered necessary. Use of specification to define the quality of the building materials to be used, for example; treated timber rather than untreated timber. Use an impartial expert to assist with this task, even if you feel comfortable that a builder you know can both design and carry out the repairs. You are better to use your builder to do the work, but to use the impartial expert to do the detailed drawings, write the specification and carry on site inspections.
2 Building Permit – A building permit is usually not needed for repair and maintenance of existing components. On the other hand, structural repairs or alterations generally require a permit. If in doubt, ask your local municipality, they have the experience of what has been required in other leaky building repair projects. Their building inspectors will also monitor the work to ensure it complies with current Building Code.
3 Building contract - Have the work done within the framework of a building contract and signed by the builder and you as the homeowner. A  Building Envelope Engineer can be hired to draw up the scope of work for you building and details to be included in the contract. This ensures you know what it is likely to cost and that you have control over the quality of the building materials used.
4 Repair work – The same Engineer can also be hired  to supervise the repairs (this may be the person who drew up the scope of works for you), because every repair job, no matter how small, will benefit from some level of expert supervision. You will have to pay for this, but it is a good way of ensuring all aspects of the work are done properly and that the risks of further leak problems are minimized.


 

If you think your home/building may have issues with weather tightness, you need to be especially vigilant in your maintenance checks - particularly potentially unsafe balconies, guard walls, decks, and mould.

Checking for moisture

Make regular inspections part of your normal maintenance routine. In particular, look for:

  • Any cracks in the finish to the monolithic cladding.
  • Separation within any sealant joins.
  • Any signs of dampness, mould or musty smells.
  • Swelling of particleboard flooring, skirtings or window surrounds.

Watch these problem areas:

  • Fascias and gutter penetrating the exterior cladding.
  • Where roofs finish within a wall.
  • Sill flashings under windows.
  • Where guard walls/rails on decks and balconies connect to main walls.
  • Electrical, plumbing and other penetrations.

It is worth noting there is growing concern at the damage that power washers can cause when used to clean the outsides of houses. If you are concerned that a power washer has been improperly used on your home, don't wait for the potential leak to cause damage. Have a weather tightness consultant check your home with moisture meters to detect the presence of moisture in walls or the roof.

If you find problems

If you do observe cracking, staining or discoloration, engage a consultant to assess the problem before doing any repairs. We have non-destructive moisture meters which can help find moisture without removing claddings. This is particularly important if you have monolithic cladding and untreated timber framing.


Water damage

Water damage

The consultant should also be able to advise you on what repairs are needed. You should also look at your options for remedies.
Photograph any damage you find, whether it is a minor repair or something requiring extensive remedial work, and date the photograph in case you need to make a claim later.

Balconies

Look out for risk factors and warning signs that show potentially dangerous rotting around balconies. If these structures collapse from water damage and rot, they could cause serious injury.
During the course of your maintenance check for:

  • Deck clearances that will allow water to drain away. There should be at least a 3mm gap between the decking boards and a bigger gap, up to about 12mm, between the house and the deck structure.
  • Bolts and flashings for signs of rust which may appear as a blackish staining around the bolt hole.
  • The deck surface for slime or mould. This should be cleaned off to reduce the chance of people slipping.
  • The step down from the doorsill. It should ideally be about 50mm deep but can be less if the sill is well sheltered.
  • A slope on the balcony floor – you can check this by running water onto it and making sure that it runs away to the drain outlet. If it ponds, especially against the building, the balcony should be rebuilt.
  • A clear gap (minimum of 35mm or more) between wall claddings and the floor of the balcony to stop water being drawn up into the wall cladding material and wall framing. Clear this gap of any dirt and leaves.
  • Cracks in balcony junctions which will allow water in and cause timber to rot. If the guard wall is covered with a proprietary cladding, it is a good idea to seek recommendations for any remedial work from the cladding manufacturer, as it may still be under warranty.
  • Drainage – if there are solid balustrades there should be outlets for the water to drain. Clear the outlets and overflows of debris, dirt and leaves.

In all cases, take photographs of any damage or design defects and date them in case you need to seek other remedies.
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Dealing with mould

Be careful when dealing with any timber in your house that appears to be infected with mould. There could be a health risk.
Anybody removing wall lining, particularly if there is a history of dampness, should take care. At the very least facemasks should be used when removing lining and rooms should be well ventilated.
For advice about dealing with mould, read the following fact sheet on the CMHC website.  http://cmhc.ca/en/co/maho/yohoyohe/momo/momo_005.cfm

Maintaining open timber decks

Open timber decks constructed with durable treated timbers are less likely to be of concern than enclosed balconies. However, the following are things that should be checked.

  • Look at where the deck meets the wall of the house. Is there anywhere that water can sit or leak into the house?
  •  Do the flashings take water away from the house wall and allow it to drain away?
  • If the cladding relies on paint to keep the water out, is that coating continuous or is there any point where water might penetrate?
  • Check whether there is any sign of timber beginning to decay.  For example, is there any sign of excessive cracking or 'softness'?
  • Is there proper waterproofing around the cantilevered joists or around other joists that penetrate the house wall?
  • Are the balustrades or posts correctly connected to the deck or balcony structure? They should not wobble.
  • Check the tightness of bolted connections to ensure nuts are secure, especially on balustrades and handrails. Also check where posts are bolted to beams, or where beams are bolted to the house.
  • Check that galvanized steel connectors are not corroding.

Maintaining solid decks

Solid decks on wood frame buildings are generally comprised of cantilevered joists, plywood decking, a membrane and guard rail. Some decks have a drain on the surface which should be checked periodically, on others the water runs directly over the sides. All structures require some maintenance, and from time to time the following things should be checked.

    • Check whether there is any sign of timber beginning to decay.  For example, is there any sign of excessive cracking or 'softness'? Timber may appear sound from the outside but, if you are not sure, poke it with a screwdriver to see if it is soft underneath (to do this you may need to look underneath the deck and at where timber meets or runs across other timber).
    • Check the tightness of bolted connections on the safety barrier, and ensure they are securely connected to the deck structure.  The barrier should not wobble.
    • Check the membrane for damage, wear, cracking, overlapping joint failure and curling off the drip cap flashing.
    • Check all caulking for failure.
    • Ensure water runs to drain or off the deck without leaving puddles. Slope should be at least ¼”/Ft
    • Ensure there is air movement in floor joist cavities.