Gilles' Outlet

February 19, 2007

Rebuilding and insulating an attic hatch

Filed under: House Remodelling — Gilles @ 5:23 am

An attic access hatch made of drywall is replaced by a plywood board. Insulation is added and the opening is weather stripped. Latches are added.

Skill Level: 2 (Basic)

Time Taken: A Couple Of Hours

In Washington, the recommended R-Value for attics is R-38. Building codes call for the hatch to be insulated at the same R-Value as the attic. Without insulation, an attic hatch is basically a large hole in the ceiling through which warm air can easily escape from the house.

Left: the access seen from the attic. It is framed with 2×4. It is difficult to see but the access panel rests on a 1/2 border all around the opening.

Right: the current access panel: a piece of 1/2 drywall without insulation. Such a board has an R-Value of 0.45. It is an easy way out for warm air.

The brown material around the hatch is a form of insulation called silvawool.

I cut a piece of 1/2 birch plywood to the dimensions of the existing access panel. I chose birch plywood because this is what I had.

Any other type plywood would have been fine. I would avoid OSB (Oriented Stranded Board) because its rough surface shows through the paint.

A table saw would have made this task easier and faster but I do not own one so I clamped a piece of aluminium and used it as a straight edge to guide my circular saw.

I used a 100 teeth fine blade specifically designed to do smooth cuts and minimize material chipping. A framing blade would have left rough edges.

I primed the best side of the board with a good quality latex primer. I let the board dry overnight and applied one coat of good quality latex paint. After the first coat dried, I lightly sanded it with a sanding block equipped with 220 grit paper. A second coat of paint was then applied.

The board is going to be visible at the ceiling so I used a flat sheen paint to match the surrounding areas.

I cut four pieces of 2” foam insulation to the exact size of the wood board. I used a utility knife with a long blade and proceeded in multiple passes. A table saw or a manual saw would have worked too.

Four pieces of this 2” foam insulation at R-10 per layer stacked onto one another will provide R-40.

Left: I removed all traces of dust on the back side of the board and applied a generous bead of construction adhesive.

Right: The bead of adhesive. Notice how the bead goes near the edge without being too close so it won’t ooze all over the place when foam pieces are stacked and held in place. 

 

I drove a few 2 1/2” wood screws at the corners, center and around the edges to hold the first piece of foam to the board.

The foam board is 2” thick and the plywood is 1/2” thick so I had to be very careful not to drive screws through the plywood.

It is easier than it looks: hold the foam tight on the wood and drive the screw. Stop when the impact driver starts impacting. You can then verify the depth and use the impact driver to do the last half turn.

Left: The four pieces of foam stacked onto each other. The white wooden board can be seen at the bottom.

I used a couple of cans of paints to hold the boards as the adhesive cured.

I could have used a few large C-Clamps but I would have had to protect the top foam board to avoid marring it with the tip of the clamps.

Right: Not all boards were exactly the same dimension. This is OK since this part will be concealed in the attic.

If this becomes a problem, they I can always be trimmed with a saw. 

 

Left: A piece of self adhesive "D" weather stripping. Strips can be separated by making a small starting cut in between them and pulling them apart.

 

Each "D" strip is 3/8” wide and 1/4” thick.

 

Right: I installed weather stripping (one D strip) around the attic opening. The hatch will rest on it and prevent air infiltration.

 

Left: I replaced the attic hatch with the one just built. It fit snugly and looked great without the popcorn texture.

Right: However, there was a visible gap on the short sides of the hatch.  This is not good because warm air will escape through this gap.

In fact, I could feel a draft when I took the picture.

 

Left: To create a tight seal, I installed the rotating part of a sash lock on both short sides of the hatch. 

Right: With the attic hatch in position, I marked the location of the strike plate on the wall.

The strike plate was positionned so when the lock is closed, the hatch is pulled down. This compresses the gasket enough to create a tight seal all around the hatch.

The lock came with 1/2” screws which were too short (the drywall is 1/2”) so I secured the strike plate with 1” drywal screws. The head of the drywall screws fit snuggly into the countersunk hole of the strike plate.

 

Left: I cut the drywall so the index of the sash lock could freely rotate into its strike plate. 

Right: The sash lock after installation, in closed position. Notice the gap is now closed.

Left: The hatch before insulation and weather stripping. 

 

Right: The new insulated hatch with weatherstripping and sash locks.

Tools Used:

  • Cordless Impact Driver
  • Cordless Circular Saw
  • Tape Measure
  • Utility Knife  
  • Basic Painting Tools
  • Caulking Gun

Materials Used:

  • Birch Plywood 1/2 thick, approximately 24” x 30”
  • Latex based Primer and Paint
  • Rigid insulating foam R-10 (2” thick)
  • Construction Adhesive
  • "D" Self Adhesive Weatherstripping
  • Two sash locks 
  • 2 1/2" Wood Screws

Leave a Comment »

No comments yet.

RSS feed for comments on this post. TrackBack URI

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

Create a free website or blog at WordPress.com.