This guide will help you decide which Therma-Dome cover is the best fit for your application.
Pull-Down Attic Stair Covers
Factors to consider when choosing the right cover for your Pull-Down Attic Stairs include
- Attic insulation type
- Attic floor type
- Desired R-value
Attic Insulation Type
If your attic floor is covered with loose-fill (or "blown-in") insulation, you will need some sort of an insulation dam in place to prevent the insulation from falling through the stair opening and into your living space. You could build your own insulation dam, or you could take advantage of the integrated insulation dam available from Therma-Dome.
The Versa-Dome™ cover can install in this way. Air sealing gaskets are incorporated into the design. It is available as an R-13 or and R-40 cover.
Attic Floor Type
If you have a solid floor deck in your attic, the best option would be to install a cover that lifts off in its entirety for unobstructed access to the attic (for storage or maintenance). The edge of the cover should have some sort of gasket that ensures an air seal against the floor, blocking any drafts between your attic and living space.
The Versa-Dome cover can install in this way, but since it is relatively new to market, it may not be available in all regions. The "Legacy" stair cover is more readily available.
The "Legacy" cover has an R-13 insulation value. It is stocked by many distributors around the country, and it can be shipped anywhere in the continental US fairly easily.
The Versa-Dome cover is still relatively new to market and, although it is available to any distributor, it is less commonly a stock item. It is available with an R-13 or an R-40 insulation value. Like the Legacy cover, the R-13 Versa-Dome cover can ship fairly easily. The R-40 version is quite bulky and must be shipped by motor freight carrier. This freight cost could as much as double your total cost for the kit.
"R-value" measures how effective an insulating product is at slowing the transfer of heat. The higher the R-value, the slower the flow of heat.
In many cases, Pull-Down Attic Stairs offer very little insulation (perhaps an R-1 or less, depending on the thickness of the door and how tightly it seals). Reviews of some products on the market that don't even claim an R-value may say what a tremendous difference the cover makes, but this is truly a "something is better than nothing" scenario. Blocking the draft is just as important - if not more important - than adding R-value over your attic staircase. Unlike other stair covers on the market, all Therma-Dome products block the draft AND add R-value.
The difference between an R-13 and an R-40 cover will probably not be noticeable, even with the use of an infra-red camera, if the cover is properly installed and does a good job of sealing to stop air flow.
If you want a higher R-value (for example, to meet code requirements or "green home" certification requirements), we do have R-40 covers that will comply with the latest specifications. However, if you are out of the service area of any distributor that stocks the R-40 cover, the cost to ship this large item will as much as double your total cost for the cover. If you can use the R-13 cover as a base, a more cost-effective solution would be to purchase rigid foam board locally and layer it up on the attic side of the cover to obtain the desired R-value. Most of our distributors also stock rigid foam board that you can use for this. Be sure to use foam-safe adhesive.