Does any one have any experience with repairing structural wood with 2-part epoxies? I'm not referring to simply patching surface areas with pastes or putties, but more along of the lines of injecting liquid two-part epoxy into structural wood in situ in order to fill voids and cavities from insect damage or dry rot and to force moisture out.

 

I have a lot of experience myself using epoxy in fiberglass boat repair, with much success. But the problem as I see it regarding wood is that a fiberglass hull is supposed to be totally stiff and stable. Whereas wood is going to expand and shrink. The argument against is that wood movement is going to work against those parts of the same wood that have been saturated with epoxy and immobilized, and that this might in time result in more damage and undermine the structure. The argument for is that if the wood has been severely compromised anyway, why not inject it and make it into something stronger than it had been? Especially if the wood has historic value and the only alternative would be to replace it.

 

Any opinions on different brands? E.g., WEST Marine vs. Abatron?

Tags: Epoxy, Repair, Structural, Wood

Views: 2500

Replies to This Discussion

I would say it depends on the size of the repair.   

 

Basing this answer on my hobby of turning wood bowls.  I use some spalted wood. This is rotten wood.  Turners stablize punky areas of a blank so it can be turned.  We use Super Glue, 2 part Epoxy, and other wood stabilizing products.

Typically these areas are relatively small.  A Turner will not get too worried about the wood moving and the stablized part not moving.

So now we apply this to a piece of wood in a historic house.  How large - and in a house, what is the orientation and purpose of the wood?  

 

Size and Orientation:  Wood moves across the face, not from end to end.  Think of your board as a bunch of straws.  A 2x4 (brand new or 100+ years old) will have the open ends of the straws at the ends of the 2x4.  So moisture movement will not occur in the length of the board.  It will occur across the 2 inches or 4 inches of the 100 year old board.

You have to look at that part of the wood that will be stabilized and think it through.  Which way will the wood move?  The stabilized joint may or may not cause a problem.

 

My, very limited, experience with historical buildings, I've done an audit for a period home owned by a City Historical Preservation Staff member; was that if a piece was replaced it had to look like the original.  Windows were the discussion item.  It was OK to replace the rotted sill of a window, because that was a restoration.

 

I would appreciate more input on this one.

 

 

Both will work fine, though I generally prefer WEST system - I haven't seen any issues created with them as far as expansion & contraction - Bondo on the other hand can pop out. WEST systems has some really good info on their site for binders, fillers, etc... which I highly recommend checking out.

 

For deep injections - I would lean more towards Abatron, though I try to get all the bad wood out where possible

 

For window profiles and others - I trim down one of those cheap plastic putty knives & press the material in as much as possible before pulling across it once

Yes, Sean!

 

West System is the best.  The cost is higher than some, but not as bad as a few others.  You can buy various open times.  I know guys that like a 30 minute open and others that like 5 minutes.

John and Sean, thanks for much informative feedback. One thing that just occurred to me regarding wood movement is that, in very, very old wood, all of the natural moisture will be gone from the wood cells (all natural drying and shrinking is over), so any movement should be due to ambient temperature and relative humidity only. If temperature and humidity are managed and held relatively constant, there should be no wood movement. So for very old interior wood that's reasonably well protected from any encroaching moisture, relative movement between stablilized and unstabilized areas might not be that much an issue. (But I can't claim this with any certainty).
With all due respect, Why is this conversation going on in Home ENERGY Pros? This is a conversation for rebuilding or hobbying, but not for residential building energy performance.

John,

 

Wood never drops below about 6% moisture.  It will move up and down from there, depending on the relative humidity and temperature.

 

Thanks John!

Hi Kevin,

It's a relevant question to the extent that it could be an aspect of the repair and preservation of historic sheathing, roof decking, siding, historic windows/window framing, etc., as part of (or perhaps as a prerequisite to) the energy retrofitting of an historic structure. To some extent, it also presents something of a requirement for the indoor environment in terms of control of moisture, temperature, and ventilation. I would agree that it's decidedly not relevant to more general aspects of energy auditing & retrofitting, etc. But for this particular group, I think it's reasonable and not necessarily off-topic. (Same goes for an earlier question about how to deal with dry-laid stone as part of sealing/insulating an historic foundation, just as an example). Anyway, thanks for joining the Historic Home group, Kevin, and thanks for commenting.

~John

Yes John, I have 25 years of experience using two-part marine epoxy.  I live in Sacramento, California and work in Sacramento and the San Francisco Bay Area. I use the Smith & Co. epoxy system out of Richmond California. It is sold in local retail stores as 'Restore-It' and on the East Coast through the Rot Doctor, with his label on the product, Jamestown distributors and Star Distributing. I was told all have web sites. The owner of the company, Steve Smith, has gone to great lengths to develop this product to expand and contract to the woods movement. You can reach him at 510/237–6842 for further information.
A few years ago I visited John Leeke (www.historichomeworks.com) in Portland Maine, where I co-taught a class on window restoration we dubbed "The Battle of Epoxy". John uses the Abatron epoxy system. We concluded that the various epoxy products all have pluses and minuses, and all used properly, should perform well.
While I'm familiar with the West Marine and Abatron the proxy systems, I like the Smith system for several reasons. First, both the penetration of proxy and filler art equal 50-50 mixes , unlike the West system and others that are a 70/30 mix. I always seem to run out of hardener the 30%, before I finish the resin the 70%. While the Abatron system is also a 50/50 mix, it comes out like thick syrup and takes 20 minutes 'mix time' before application. The Smith system is ready to go and has great penetration viscosity. The Abatron stealer can be thinned to be more penetrable, but takes more time.
Second, what I also like about the Smith system is the 'pot life' of the pretreating sealer last a long time, and if I have some left over, I can put it in a sealed container, put it in a refrigerator for up to 48 hrs. or so, and still use it. I also like that it cures slowly, so that it can penetrate deep into the wood fibers.
As for the use of the filler material, while I like the Abatron filler, for one can mix it by hand, I find one has to thin it down to make sure it gets deep into some very irregular places. While the Smith system filler well slump or deform (not shrink) in certain applications, I use a plastic sheet material from Tap Plastics as a form to hold it as it sets and cures.
And last but not least, I usually buy my supplies from Smith when in the Bay Area, I can get some in a pinch from many retail stores that carry Restor-It.
Please excuse my delay in responding. I'm new to the blogispher and not the fastest typer. I'm trying to use Mac Speak but it is not co-operating with me.

David, thanks very much for this very detailed and highly informative reply. I have worked with WEST system a lot in fiberglass boat repair, and am familiar with their hardening and filler options, and yes, like you, I've also ended up having to toss unused resin when the hardener runs our first! A bit frustrating. I am in the process of trying Abatron, but haven't used it seriously on any projects yet. The Smith & Co. epoxy I've heard of, but haven't tried. But that one is now at the top of my list to evaluate, given your descriptions of it.

Am also looking forward to hearing any thoughts you might care to share regarding what you've done to control thermal transfer with historic windows. I think these fenestration issues are really important ones for energy efficiency and establishing a good thermal envelope in an older home. And there is no need for apologizing for a delay. There is no time limit here for replying. I am glad that you invested so much time in providing us with a highly compreshensive and very useful report. And if there is any help I can provide you with regarding finding your way around the blogosphere, etc., please do not hestitate to ask. Thanks! 

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