DECK PREPARATION

New Construction – Select plywood, 5/8 or 3/4″ t&g should be installed minimum 24 hours before a membrane is installed to allow the plywood to aclimatize.  Even if the plywood gets wet, this time is very important. If you cover the plywood, don’t let water get trapped.  It is better to let it get wet and be open to the air to breath.  If good exterior plywood is used, a rain shower should not harm it. The membrane should be installed before the wall cladding and guard rails are installed. This allows the cladding to counter the membrane and the rail base plates or notched posts to sit on top of the membrane.  In order to avoid cutting the membrane it is recommended that wood posts be notched and lagged or bolted to the fascia with the post sitting on top of the membrane. If posts are to go thru the deck, then they should be installed before the membrane goes on. This way the membrane can be applied up the post 1 or 2 inches depending on whether the posts are going to be clad (preferable) or just painted (special up stand required). If this is NOT done, water will soon get into the wood around the posts regardless of caulking, destroying your deck long before its time.

Where ever waterproofing is strongly dependent on caulking, this will be the weakest point of the deck and in areas that are directly affected by the elements and where water tends to pool is especially critical. Pooling on decks is inherent due to limited slope and irregular wood contours.  Other factors causing pooling are, wood shrinkage, settling, poor lumber.  Proper construction and slope will keep this to a minimum.

Membrane Shrinkage – Shrinkage can cause what we call tenting (lifting from the surface).  This shows up more in the heavier membranes such as the roofing grade, but may also occur in a poor installation of lighter grades as well. If care and proper installation procedures are used, this can be avoided.  There are some types of membranes which are susceptible to shrinkage in certain instances.

Rule of thumb – for sloping a deck is 2% or about 2 1/2 inches in 10 feet.  Too much and your deck feels like a ramp.

Plywood should be select grade and should be screwed or nailed with flooring ring nails for best results.  Screws are OK but they tend to be more damaging to the wood surface. The  better the plywood, the better the finish and the less chance of stain migration.  Crown of floor joists should be up.  Because the membrane is applied to plywood and NOT a flooring underlay such as with kitchen floors, as well as being outside in unstable conditions, a kitchen floor like finish is difficult to achieve.

Avoid drains if possible, they clog and demand precise sloping of the deck to the drain. In new construction the low spot today may NOT be the low spot in a few months due to wood shrinkage, settling, etc.  If water must be contained it is preferable to use a gutter around the deck.  This allows for wider dispersion of water from the deck, thus less pooling.  If water is to run off the edge of the deck, a wood nosing preferably a 1 x 2 should be fastened to the edge before deck flashing and membrane is installed.  This will prevent most of the water from running down the face of the deck which causes staining, a common problem.

For roof decks over heated areas it is important to ventilate the space between the deck floor and the insulation below usually with perlins (wood cross members over the floor joists to create an uninterupted air space for ventilation across the under floor) to prevent condensation.  There must be an outlet for circulation either thru the soffits or vents in the exterior wall.  If allowed, moisture will build up on the underside of the plywood due to the cold plywood next to the warm insulation causing condensation and thus rot the plywood from the bottom up, until one day your foot will go thru the deck.  This is a major problem in many renovations.  Pro Deck Ltd. is well experienced in this area and can be consulted for recommendations.

Curbs and pony walls around decks should be sealed and flashed properly to prevent water from going down the inside and in the case of a roof deck, the walls often require venting.  If water does get into this wall, the water finds its way under the deck membrane then lifts it from the deck surface.  The membrane will lift from the surface and the problem enlarges.  This is an area NOT given the carefull attention it should.  In addition to a metal flashing, a self sealing bituminus membrane should be installed on top of the wall before the flashing, thus any nail or screw penetrating the metal flashing will be sealed at the membrane.  The primary purpose of the flashing is to protect the membrane and finish the wall.

Building a deck onto an existing house – In most cases we no longer recommend cutting the wall cladding (stucco or siding) so that the deck ledger board can be fastened directly to the house header or trimmer joist.  This could interfere with the performance of the building envelope if special care is not given to the wall detail.  We prefer to fasten thru the cladding. This generally is quite acceptable structurally.  The membrane can then be put up the wall and sealed by means of a cant strip or metal flashing.  This method does need further consideration when dealing with a roof deck.  Consulting with a deck professional like Pro Deck Ltd. is essential in this case.

For existing decks with drip thru floor boards, not less than 1/2 inch plywood is recommended over these boards to reduce the risk of warping. Quite often drip thru decks will have no slope. In many cases the easiest way to create slope is to shorten the posts, however, in some cases, tapers must be used under the plywood to create slope. Here not less than 5/8″ plywood must be used. This requires that there be enough room under the door sills.  Where there is little room under the door sill, the deck could be sloped back to the house with drains installed at the house.  This is done only as a last resort.

Caring for your vinyl deck membrane – Most of the better quality membranes can be swept and mopped just like a kitchen floor.  The poor quality ones have rough surfaces trapping grit, sand and mildew and cannot be cleaned in this way.  The safest method for cleaning any vinyl is with water and mild soap using a stiff brush, one with a handle to make it easier on yourself.

Avoid harsh cleaners and solvents.  These may remove the colour and break down the plasticizers and UV inhibitors in the PVC reducing its resiliency.  For stubborn stains such as those from rust, some paint, leaves, etc., a special cleaner is available which is expensive.  We have some feed back that “Goof-Off” works well for stubborn stains but care must be taken to use it sparingly, rinsing well after use.  Always try a test area first.  Power washing does a great job but CARE must be taken not to lift caulking from critical areas. If there are any weak seams, these may separate and lift and will have to be fused closed.  Caulking should be checked annually for separations.

Some of the poor quality vinyl membranes smell and the older they get the worse the smell gets.  Some are so bad, people have difficulty eating out on their deck.

If this is your problem, TRY THIS:

Paint the membrane with a high quality elastomeric acrylic coating.  The older the vinyl the better the coating will adhere.  There is no guarantee how long it will stand up, but I have seen some that have done very well.


 

GUARD RAILS

Our standard “Vista” posts are component design allowing for a custom built system while welded aluminum posts which are not only ugly, as shown below, do NOT.

 

Our metal railings are made from tempered aluminum extrusions which substantially improves the strength of the metal.  The tempering in the metal is destroyed by welding and weakens the aluminum by as much as 33%.  This is well substantiated by the number of broken welded base plates we see.

We use #14 stainless screws for fastening. Many installers use #10 or #12 galvanized fasteners which will rust if they sit in water, as shown above. Just another way some companies cut costs. Using inferior caulking to seal the penetrations or non at all is another way some companies cut costs.

Normally 5mm tempered glass is quite adequate, but for a more robust rail, 6mm can be used.  Use of 4mm glass is another way some companies cut corners.

Tempered glass is the choice over laminated glass or acrylic panels. Tempered glass is up to 6 times stronger than standard glass. Laminated is expensive especially if tempered is used on both sides.  Acrylic scratches, cracks & fogs easily & tends to warp.

The obvious advantage of aluminum rail over steel is that it doesn’t rust & unlike wood, it should never need painting provided a high quality coating is used.
Engineered aluminum railings such as ours, if built & installed properly, easily exceed building code requirements.  Post spacing, sizing & bracing specs. should not be compromised for price.
JUST AS IMPORTANT  as the rail specifications is the material the railing is being fastened to & the fasteners themselves.  As is the case with most things, the rail is only as strong as the material holding it in place.

Case in point:  Fasten a post (aluminum, wood or steel, it does not matter) onto concrete, now fasten a similar post onto a wood deck made of plywood with a single trimmer joist.  Now try to move each post back & forth; the difference in flex movement on concrete compared to the wood becomes immediately evident regardless of which post is used, steel, aluminum or wood.  This is why any properly built deck should have at least a double trimmer joist or backing as well as backing in the wall where the rail is to be fastened.

Caring for your railing:  If the coating is quality, it can be washed & polished the same way you would do a car.  Not only will this protect it from U.V. which will discolour & break down the coating, but will make your rail more resistant to scratches, mildew & chalking.

There is a popular misconception that the best coating for a rail is powder coating.  There was a time when this was true, however, with the new high tech automotive finishes available, powder coating is no longer better.  Powder coating is highly mar resistant, a big plus for exterior railings, but does not hold its gloss as well & chalks (oxidizes) faster.

In a rail system where stainless fasteners were NOT used, these should be checked every couple of years for integrity. Rusting fasteners, and galvanized will rust, not only ruin the look of a rail but weaken the rail system as a whole……. eventually creating a dangerous guard rail.  Replace these fasteners preferably with stainless steel & re-seal all deck penetrations at the same time with high quality caulking/sealant.

Preventative Maintenance could save you a bundle in the long run!  Doesn’t that go with anything?

Some sites to visit!

Building Code


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