Posted by: SherlockHomesSY | 7 Feb 2011

51 Attic Holes: Scuttle Holes

Scuttle Hole Cover

Click to DOE Home Energy Savers

SCUTTLE HOLES

A scuttle hole is usually a 2’ x 2’ entrance hole to the attic, covered by a panel.  Often, the panel fits badly and rarely insulated.  The result is probably the biggest air leak in the house with a 20% reduction in attic insulation value over 1000 sqft.

I still haven’t air sealed and insulated my scuttle hole because I haven’t found a solution I liked.  I’ve been designing it and redesigning it since 2007.  (The picture is typically found.)

I been through a lot of scuttle holes: some are easy to work with and others are a pain because of the construction details around the scuttle hole.  I’ve searched in vain for an easy DIY project or off-the-shelf product that does both the air sealing and insulating job it’s supposed to do.  Most of them are under-insulated or deny the realities of the abuse they must endure while getting in and out of the attic.

Our next post is the DIY Attic Scuttle Hole Cover, where you’ll find the a-ha moments leading to  how I’m going to build mine.  It’s one I can easily recommend and adapt to almost all attics!  It wasn’t until I wrote the requirements for this post that it occurred to me what to do.

What We’re Trying to Do (Objectives). The goal is to make the entrance as air tight as possible and ideally, insulate it to the same value as the rest of the attic.  Not easy to do because people have to get in and out of the attic without ruining it.  And, it’s got to be easy to put back.

What Needs to Happen (Requirements)
1. The panel, when closed, needs to create a tight seal, much like a refrigerator
2. Use rigid insulation to avoid having insulation fall out when the panel is moved
3. No air leakage around supporting trim is allowed
4. Avoid air movement around the ceiling panel insulation
5. Have an easy place to put the panel out of the way when removed, without messing up the finish
6. Ensure the largest piece of heating and air equipment can fit through the hole
7. Don’t leave foam exposed in an attic with a gas furnace or water heater in it
8. Insulation against the scuttle hole frame  isn’t allowed to fall out

What to Look for When Finished (Test)
1. Put a light around the entrance in the attic and close the door.  No light leaks allowed.
2. Look for rigid insulation tightly fitting against the ceiling panel
3. Confirm air does not easily circulate around the insulation
4. Remove the panel, crawl in and out of the attic, and put the panel back.  It should be easy to do quickly without falling apart
5. Determine whether the hole is big enough to get heating and air equipment in and out

Basic Idea (Process). To build an insulated scuttle hole cover, the main problem to solve first is how to get the lid the off the opening.  That depends on design, particularly if truss chords (roof deck support boards) are in the way.  Where will you put it when you take it off?  Make sure there’s enough space for the lid and the entrance isn’t covered in anyway.

The frame around the scuttle hole needs to be built tough.  A ladder may lean on it.  It will surely have to carry a person’s weight as it is crawled over and kicked.  May I suggest at least 300 lbs for man and tools?

If an air handler (inside unit) needs to go in the attic make sure there is a way to take the frame apart, if necessary, to get it out!

Somehow, air circulation needs to be limited around insulation, usually with one or more air-tight seals.  The sealed surfaces need to be in alignment with each other, usually level.

Warnings & Cautions

If there is a gas appliance in the attic, be sure foam is sandwiched between something like plywood/OSB and drywall.  The issue is the smoke and flame spread indexes.  Foam burns fast while creating a lot of toxic smoke.

If gas appliances are inside the house, be aware that if your house is close to or already considered air tight, any natural draft gas appliances could backdraft.  Be sure to get a combustion safety test done if you’re at all close on the air infiltration numbers.

Recommendations

Professional Recommendations. It took me over 3 years to find a solution that works.  This is not something routinely built for houses.  If it were, many of the construction hindrances around the scuttle hole just wouldn’t be there. Show these requirements and test conditions to your contractor and then ask a lot of questions about their solution(s).  Don’t be shy about showing them ours because the light bulb just might come on for them too!

Hint: The picture in the article is typical, but it doesn’t work very well. The article on Attic Covers is okay though.

DIY Recommendations. Assuming basic tool knowledge and the ability to cut the frame to exact dimensions with a table saw, this is an easy DIY project.  The only special tool you’ll need is a thin-kerf plywood table saw blade to cut the foam.

Expect to use a little creativity to adapt your solution to the construction around the existing attic hole.  This is the major reason there are no real good off-the-shelf products you can buy to do the job.

Resources

Here’s a technical bulletin from Soutface Energy Institute on Attic Covers.

In Conclusion

Oh, alright, I’ll give you a sneak preview on what finally occurred to me that makes this project work easily.  I’ve only seen scuttle hole covers to that go into the attic before taking them out.  I’ve also seen hinged scuttle hole covers that drop down.  How about a ceiling cover that drops down  and out while the  lid that pops into the attic?  See our next post: DIY Attic Scuttle Hole Cover.

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