Two of the homes will have insulated raft foundations. This allows the house to rest directly on the ground, keeping the floor warmer than if it were elevated on piles. A thick mat of spray foam is designed to prevent heat loss from affecting the frozen ground, and a cooling system was also installed in the gravel pad to chill the soils if needed.
CCHRC is demonstrating an innovative foundation design at the Sustainable Village. Two of the homes, sitting on permafrost about 9 feet deep, will be built on steel piles, a common method for building on frozen ground. The other two, situated on stabler soil, will have an insulated mat foundation.
Builders laid the mat foundations last week. They include a geotextile mat placed directly on the soil with several feet of gravel on top. PVC pipes are embedded in the gravel in a grid formation as a backup cooling system. Resting on the pad is a steel floor assembly. Spray foam was applied against the entire system for a monolithic layer of insulation at least 10 inches thick. This is designed to prevent heat from inside from transferring to the ground. Temperature sensors were strung about 10 feet down into the soil to monitor any changes. If needed, cold air could be circulated through the piping system in the winter to lower the temperature, as insurance against shifting ground.
Here’s a look at the pad preparation.
Winter is looming, but there is still time to attack a fall home maintenance punch list before it gets too cold. In addition to a boiler tune-up and chimney inspections, there are a few more details worth considering.
Now is the best time to make sure your roof system is in good working order. It’s not too late to replace shingles, add snow stops, patch leaks, or replace any missing fasteners on metal roofs. Now that the leaves are down, the gutters are ready for inspection. In the spring, gutters clogged with frozen debris are virtually impossible to clean and can cause melt water to overflow and run down next to the foundation and into the basement or crawlspace. Check the downspouts too. They should be unobstructed, firmly attached, and pointed to direct water away from the house. While you are walking around the house, check the grade for drainage. Surface soils will remain unfrozen for a little longer so it’s not too late to do any last minute dirt work to ensure spring run-off is directed away from the house. Inspect any heat traces to make sure they are in good (and safe) working order. Replacing a heat trace now is a lot less hassle than a frozen waste or supply line in the winter. If you have any concerns about the safety of a heat trace – particularly if it’s older—consult a professional. A malfunctioning heat trace can be a fire hazard.
If you have an HRV system, make sure all parts of the system are in good working order. Alaskans tend to spend a lot more time indoors during the cold periods, and good ventilation is critical. An inspection should include a look at the supply and exhaust grilles on the outside of the house – not just those belonging to the HRV, but also dryers, range vents, and bathroom fans, especially if they are close to the ground where the intake can become clogged with leaves, grass, or other debris. If an exhaust damper is present, make sure it is operating smoothly. Open up the HRV and examine both the filters and the core. The cores can be removed and washed out if they’re dirty. The condensate drain and drain line under the HRV should be free of obstructions; if a trap is present, it should contain water. A properly installed HRV is designed to bring in and exhaust the same amount of air. The system should provide enough fresh air to ensure occupant health and control humidity but not over-ventilate, as excess air flow is simply wasted energy. If you’ve never had your system professionally balanced and inspected, now is the time.
If you’re planning any air sealing with spray foam, the cut-off temperature for most expanding foams is above freezing, although a few brands may go lower. Last but certainly not least, make sure your home has operating smoke alarms and at least one operating carbon monoxide detector.