When you're discussing a renovation with your contractor - particularly the budget - you need to understand what options you have for structural elements and sheathing. Sure, you could just leave it up to the contractor and hope for the best (and with a good contractor, it should all work out). But I believe the more you know about your renovation, the more control you'll have over the results.
Should you use steel beams or PSL? Lumber or LSL? Plywood or OSB? What's better? What costs more? Is it worth it? What do those letters mean?
The letters stand for types of engineered wood products, and it's worth your time to ask your contractor about them. For years, most houses have been framed with traditional sawn lumber - standard two-by-fours and two-by-sixes. Steel I-beams or solid wood beams are used where strong structural support is required.
Wood isn't perfect
Wood is a natural product, which can cause problems when using sawn lumber for building. Wood can shrink, warp and twist - which can eventually lead to wavy walls or even cracks in drywall. A piece of two-by-four may have knots or holes that make it unusable, and it will have to be scrapped, which will cost you money. Sawn dimensional lumber is limited in size to standard, smaller lengths and depths - depending on the size of the timber cut to make them. This can be a challenge for your builder when your renovation design calls for long, open spans or high ceilings that require long unsupported beams to carry the load. Unlike sawn lumber, engineered wood is strong and stable, and can be made in any size.
Engineered wood
Engineered wood is manufactured by using glue and pressure to bond together wood strands and wood fibre to produce a building product that is usually larger, stronger and stiffer than traditional wood. The manufacturing processes used to create engineered wood make it more expensive than sawn lumber for a lineal foot, but using it can save you money by speeding up installation time, and reducing waste and labour costs.
Environmental impact
Harvesting trees for lumber has a huge impact on forests. The building industry's hunger for lumber is insatiable. When you consider that the larger the finished piece of sawn timber requires bigger trees - the old-growth trees - you worry. (And it only gets worse when you find out that up to 10 per cent of a cut log is wasted in the cutting and shaping of lumber.) Engineered wood products are manufactured from fast-growing trees, such as yellow poplar and aspen, that can be harvested at a smaller size. And since manufacturers don't use large single pieces - they maximize the amount of wood fibre that is harvested from each tree. Engineered wood products are bonded by a variety of adhesives, and the manufacturing creates some waste - so they aren't environmentally perfect, but they are a step in the right direction.
Structural beams
Structural composite lumber - such as laminated veneer lumber (LVL), laminated strand lumber (LSL) and parallel strand lumber (PSL) - is used for support beams, window and door headers, and wall studs. All three resist warping, bowing and shrinking - problems that can give you sticking windows and doors, or worse. And, because composite lumber is an engineered product, it has a predictable strength and stability, which makes possible longer spans without supporting walls or posts. This gives you more design options with open, spacious floor plans.
Floor joists
Engineered joists are used under floors and in roofs. Their additional strength helps them resist twisting and shrinking and they can be cut to long spans. Because of their strength, they can be placed at wider intervals. Traditional wood joists are usually installed 10 or 12 inches apart, but some builders are using engineered joists 16 or even 24 inches apart to support the same load (minimum code). Do I like it? No. It can save the homeowner or builder some money, but it can also lead to bouncy floors.
Sheathing
Oriented strand board (OSB) is made of layers of wood flakes arranged in cross-oriented layers that are bonded together with heat-cured adhesives. OSB is much less expensive than plywood, which is why it's being used by builders all over the country in place of plywood. There are different grades of OSB for different applications. I've spoken before about how builders (following minimum code) are using low-grade OSB in place of five-eighths-inch plywood for subflooring. I don't like it - it's not strong enough and it leads to cracked tiles and grout. But if OSB is used properly, I accept it.
Skilled installers needed
A lot of contractors aren't familiar with using engineered lumber - so they resist it. A lot of "cowboys" think they know it all - and they use it incorrectly. You have to be careful when cutting through engineered lumber to install plumbing and electrical components. And most engineered wood products are limited to interior use - they cannot get wet.
If your contractor isn't experienced with using engineered wood products, stick with traditional lumber.
Or, better yet, get another contractor.
Mike Holmes is the host of Holmes on Homes on HGTV.