Renovations for energy saving
Before insulating foundation walls, make sure they are in good condition and check site drainage. Good drainage means no moisture problems once the walls are insulated. If existing moisture problems cannot be fixed, insulate the walls from the outside: at least 600 mm (2 ft.) below grade for poured concrete; from top to bottom for concrete block. Most crawl space foundations should be treated as if they were basements. There are two types of crawl spaces: “open”, where the crawl space is not heated but vented to the outside, and the floor over is insulated; and “closed” where the crawl space is heated, the walls should be insulated. There should not be any vents to the outside of a closed crawl space. If there are no moisture problems in your poured or concrete block foundation, draftproof and insulate crawl space walls for their full height. This includes the rim joist and joist space in the floor above, to at least RSI 2.1 (R-12) or RSI 3.4 (R-20) if using electric heat. Heated crawl space: close off vents after insulating the walls and installing a moisture barrier over the crawl space floor. The moisture barrier can be a 6-mil polyethylene sheet over the ground or the concrete, with all seams overlapped, weighed down with a few stones and sealed at the edges. Unheated crawl space vented to the outdoors: If you can’t insulate the walls from the interior, then the insulation in the floor should be increased to completely fill the floor joist cavity. It is most likely easier to insulate the crawl space walls from the outside than to completely fill the floor cavity, especially if the crawl space is less than 1.2 m (4 ft) high. In either case, a moisture barrier must also be applied to the crawl space floor.
In any crawl space, it may be difficult to create a continuous seal for the moisture barrier, especially if the crawl space is very shallow, or if there are posts and foundation pads in the way. The less continuous the moisture barrier is, the less successful your draftproofing measures will be. Insulating the crawl space walls—inside or outside—has the following advantages: the space is warmer; it is easier to achieve a continuous insulation and air leakage barrier than in the floor above; piping and ducting end up within the conditioned space of the house so they don’t need protection against freezing. Concrete slab foundations in renovated carports or garages can be made more comfortable while reducing energy requirements with rigid board insulation fitted between 2×2 sleepers over a continuous moisture barrier laid on top of the concrete floor.Make sure there will still be sufficient height in the room(s) after the addition of the sleepers, a subfloor and finished floor assembly.
Usually it is not practical to upgrade the wall insulation if the cavities are already filled with insulation, however; replacing the siding is a common upgrade on an older house. This is the best time to add a layer of exterior insulation with a house wrap air barrier. If at the same time you can replace the windows with better-performing units, the combined retrofit gives your older house a facelift, better energy efficiency and higher levels of comfort while saving you money on labour costs. Obtain professional contractor’s advice on how best to approach this retrofit on your house.
Ceiling/Roof Insulation – Increase to at least:
_ RSI 7 (R-40 ) natural gas or oil space heating
_ RSI 9 (R-52) electric space heating
_ RSI 5.6 (R-32) in coastal British Columbia
The amount of insulation you can add will depend on roof structure and access. It may not be possible to add more insulation between the rafters of the sloped ceiling in a dormer, sunroom or covered porch. The best solution is to have the ceiling (and exposed walls) filled with foam-in insulation, for high insulation values and a good air seal in one step. If foam-in insulation is not an option, add a layer of rigid foam insulation to the existing interior finish and then cover with a fire-rated finishing product such as gypsum board. Losing a little height (25mm/1 in. of foam + 12mm/0.5 in. gypsum board) can increase your insulation level by RSI 0.8 to 1.5 (R-4 to R-8), depending on the product used. More importantly, a well-sealed layer of insulation on the interior can reduce drafts significantly. The kneewalls can be insulated the same way. Another option is to have a layer of rigid board insulation added to the exterior as part of a re-roofing job. A professional can ensure that the upgraded roof assembly meets building code requirements.
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