How to insulate attic hatch panels is easy and effective with rigid foamboard and a few other minimal supplies. The following steps and materials could also apply to insulating an attic door.
- Rigid Foamboard – Owens Corning Foamular 150 or equivalent.
- Foamboard Adhesive – Loctite PL 300 or equivalent. When looking for adhesive, make sure the label mentions foam board, or panel foam compliant.
- Foamboard Cutting Tool – See Step 3 below
Additional products and information:
- Rigid Foamboard R Values – 1 in. = R-5 | 1.5 in = R-7.5 | 2 in = R-10
- Polyurethane Rigid Foamboard Technical Specs
- Owens Corning R-value guide by region – insulation requirements (page 6)
- Owens Corning Stairway Attic Insulator
Step 1 – Measuring Attic Hatch Panel
Remove the hatch panel and measure the dimensions.
This would be a good time to inspect the existing hatch panel, and replace if need be. Moisture may have caused the panel to swell, deteriorate, and/or mold.
Typical material uses are 1/2″ – 3/4″ birch plywood or MDF (fiberboard). Any hardwood and pre-sanded plywood is fine. Don’t use rough faced sheathing sheets designed for walls and roofs.
Home improvement stores will carry any of these products and should be able to cut to size. Check local lumber yards to buy half (4′ x 4′) sheets if not needing a full sheet (4′ x 8′) to cut from.
Step 2 – Calculate Foamboard Amount
Calculate the R-value and amount of rigid foam material needed.
Note: In cold climates with values as high as R-60 for the overall attic area, you will not need to match the exact R-value to insulate attic hatch panel. On my own home, there was a 5° variance (infrared thermometer) between the surrounding insulated ceiling, and un-insulated hatch panel. Just adding and R-30 (3 ea. x 2” thick rigid foam layers), resulted in an even temperature across the surfaces.
* There may be an obstruction in the attic that requires tilting or sliding the panel out-of-the-way in order to gain full access. This may limit the thickness of the rigid foam being added, otherwise proper clearance will pose an issue. Obstructions may include- (i) Plumbing vent pipes (ii) Slanted ceilings or walls (iii) Bath fan venting
Step 3 – Cut Foamboard to Size
Cut rigid foam to dimensions. A good rule of thumb would be to deduct an 1/8″ on each side to avoid any fitment, or clearance issues.
Your local home improvement store or other supplier may offer cutting service. If not, a simple straight edge and utility knife will work: score the material (roughly 60-70% through)…then snap the pieces apart. See our OLFA knife cutting review. Other cutting options include: (i) A drywall jab saw or similar hand saw. (ii) An electric knife or long serrated style bread knife.
Step 4 – Assemble Foamboard Layers and Attic Panel
Apply rigid foam sections to wood panel using foamboard adhesive (mentioned above). Follow manufacturers instructions. If a caulk / adhesive gun is not available, buy the cheapest version for this type of project where consistency and flow control is not an issue.
Tip: This may not be necessary, but I like adding some weight to the final assembly during the curing process. This ensures the pieces remain flat and tight against each other.
CAUTION: If constructing the panel and layers of insulation outside of the attic space, calculate how many insulation layers will allow the final assembly to fit through the access hole. Adhere the remaining layers in the attic space if need be.
The most limited dimension will be a square and rotating the assembly 45° through the opening. A rectangle will allow the shortest edge to be fed straight through the long side opening.
The square assembly shown takes into consideration using 2″ rigid foam per layer, 3/4″ wood panel, and a 1″ ledge on each side of the opening for the attic hatch panel to rest on. e.g. 28″ x 28″ opening and 30″ x 30″ panel assembly. Construction may vary.
Step 5 – Add Weatherstripping to Attic Panel Framing
Add adhesive backed weather-stripping to the inside edge of the panel support trim to eliminate any drafts. Styles to consider are EPDM D Strip, or any other low profile design that will compress and not create a large gap. All local home improvement stores will carry some variation and color.
Step 6 – Install Insulated Attic Panel
Reinstall attic hatch panel once all: adhesives, paint, etc. are dry.