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Wise use of glue on exterior work?

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Forum topic by bd1886 posted 07-08-2018 09:01 AM 1144 views 0 times favorited 13 replies Add to Favorites Watch
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bd1886

34 posts in 326 days


07-08-2018 09:01 AM

Second post here…gonna be many more.
Today I was working on a project building nice cedar gates. In building them I used a well cured pressure treated (1 1/4 inch planed/on edge) approach for the core with central cedar bead board wainscot panel and 1/2” skin, over the perimeter pressure treated core structure.
Well, tomorrow I’ll be installing the routered bead board central panel. Moisture read is very low in the wood, parts are cut for the cedar overlay on the final sides. Would it hurt to make sure the bottom of that panel gets fully glued up using waterproof glues/resins? (Washington State here…..water can be a problem.)

Now….the gates will be getting a rustic treatment with engraved wormholes artificial wear, course bronze hasps and hinges, course faux inlayed joinery plugs, you know….a polished turd look (that’s appealing (for all it’s character thing) and future finish look tuning up accepted So? It’ll be built strong, while cracking is fine, will it warp (or something else bad) due to the bottom of them not moving because of being glued up solid. Sometimes too much working (gluing) against Mother Nature can bite you in the butt I’m thinking. Thanks, all thoughts appreciated. Scott


13 replies so far

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clin

1027 posts in 1359 days


#1 posted 07-08-2018 03:47 PM

Some photos and drawings would help. I couldn’t get understand what you where describing.

As a rule, do what you can to keep water out (sealed on top and sides). But allow for water to get out (drain) using seep holes if appropriate. As always consider wood expansion and contraction in the design. This usually means a strong frame, and then a panel or boards that float or are otherwise installed so they can expand and contract without binding.

If your overall structural design is unusual, it likely means it is a bad design. The common designs have evolved based on tried and true techniques. Of course modern materials open up new design possibilities.

-- Clin

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Lazyman

3339 posts in 1750 days


#2 posted 07-08-2018 04:33 PM

Not sure that I understand either. It sounds like you you planning to wrap a structure built with PT lumber with the cedar? What are the dimensions of the cedar beadboard panel? Is it some sort of plywood? Is it intended for outside use? I think more info is needed and some pictures or drawings would help.

-- Nathan, TX -- Hire the lazy man. He may not do as much work but that's because he will find a better way.

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bd1886

34 posts in 326 days


#3 posted 07-08-2018 07:53 PM

Apologies for getting too descriptive….poorly!

Pic is worth a thousand words…..


Top pic shows it lifted up to show bottom.

Double thickness central panel with top trim being added after build…drill weep holes in the bottom plate?

Thanks guys. Scott

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Aj2

2205 posts in 2161 days


#4 posted 07-08-2018 08:09 PM

I would not glue the bottom to the panel boards if that’s what your thinking. I would add as much drainage and gaps as possible to the bottom and the panels. First good rain and every gap will be closed up tight. When the gate dries out if it cannot move back it will crack or warp.
What you can do is one single fastener in the middle of each panel board.
And then hope for the best.

-- Aj

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bd1886

34 posts in 326 days


#5 posted 07-08-2018 08:14 PM



I would not glue the bottom to the panel boards if that’s what your thinking. I would add as much drainage and gaps as possible to the bottom and the panels. First good rain and every gap will be closed up tight. When the gate dries out if it cannot move back it will crack or warp.
What you can do is one single fastener in the middle of each panel board.
And then hope for the best.

- Aj2

Great support you guys! I’ll post pics when done.

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Rich

4419 posts in 952 days


#6 posted 07-08-2018 08:28 PM

Rather than drainage holes, what about sealing it with silicone? I’m curious because I bought an 18th century panel made of approx. 5/16” metal bent into a fairly complex mesh pattern. I’m going to be using it in the center of a gate similar to the OP’s. I haven’t begun construction, but how to deal with the groove it will sit in on the bottom rail is a concern. I’m not trying to hijack the thread, since whatever solution works for one will work for the other.

Opinions?

-- Knowledge is not skill. Knowledge plus ten thousand times is skill. -- Shinichi Suzuki

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bd1886

34 posts in 326 days


#7 posted 07-08-2018 11:33 PM

Hey Rich, I am in the same boat as you here in saying “I can Handle you Mother Nature….I hope?”.
Looking back on my seat of my pants design as I cut and build? I did think of leaving an open bottom rail because why? I’ve repaired this kind of thing before in my occupation. Why did I go ahead then basically allowing “form over function” to take priority…stupidly? Latent ego!!!! (Still? Before going past the point of no return decided to talk to others….smartly.)
I’m glad I did and will now engineer my finishing flurries accordingly.

Just thought of how closeup photos of The Great Pyramids reveal that they’ve actually gone to hell.
What was I thinking…. I’m far from a “Pyramid Builder” ta boot!! Lol Scott

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clin

1027 posts in 1359 days


#8 posted 07-09-2018 12:13 AM

Pics helped a lot, but I still have a few questions. If I understand this correctly, the frame is made up of a pressure treated center and 1/2” ceder on the outside of that. The ceder overlaps the PT wood such that it forms the grove that traps the panels boards. The panel boards will be vertical?

If I have this correct, I agree with Aj2. Put a single fastener in the center of each board. I recommend a stainless steel brad. Stainless won’t rust and therefore won’t react with the tannin in the wood and make black streaks. An alternative would be stainless or brass screws. But, on the back side of the gate, you can just shoot a brad in at an angle. It will be so small it will be unnoticeable.

NO GLUE, on the panels boards anywhere. The exception would be to not use a fastener and just put a dab of glue in the center of each board.

This will allow each board to expand and contract from its center. The boards need to be spaced far enough apart that when they swell, due to rain etc., they will not push against each other too much (best if not at all).

If you need the gate to be solid (no gaps you can see through), you can tongue and groove the panel boards. Then when you install them, put some space between them to allow for expansion. Meaning don’t push the boards tightly together. Especially if they are known to be dry. For example, an 1/8” gap. The T&G will keep the gap from opening all the way through, as long as the T&G is deep enough.

It is possible to not even use a fastener in the boards and just allow them to float. The problem with this is any gap or tongue and groove spacing is not likely to be evenly distributed. So unless your T&G were unusually deep, a gap all the way through the boards could show.

I just found this wood shrinkage/expansion estimator. You can look up the temperature and relative humidity data for your area and plug it in. You want to look at seasonal, NOT daily temperature and humidity.

http://owic.oregonstate.edu/wood-shrinkswell-estimator

In any case, 2% movement is realistic. Assuming a 40” wide gate, that’s over 3/4” of total expansion and contraction.

Water will collect in the bottom frame member due to the groove that traps the boards. This is where I would put weep holes. Just drill 1/4” – 3/8” or so holes through the bottom of this. I’ve spaced these about 6” apart and used a chisel to slope the bottom of the groove towards the holes. This slope probably doesn’t do much of anything. Just don’t make the holes so large or frequent that they reduce the strength of the frame significantly.

They can’t be seen since they are on the bottom edge of the gate. That way, any bulk water can drain out. I live in a very dry climate, and I had an existing gate on my house that did not allow for this drainage. And it all rotted out in less than 10 years. We get 6” a year or so of total rain. Like I said, dry.

Remember, even rot resistance woods like ceder or PT, are just that resistant. So anything you can do to reduce the amount of time it is exposed to water, the better.

FYI, an alternative is to make the bottom a tongue and grove where the groove is in the ends of the panel board and the tongue on the frame. This way there is no place for water to collect. In your case, this would require the PT wood to stick out from the ceder and be cut to form the tongue.

Something to consider doing is to putting a slight slope on the top edge of your bottom ceder panels. The idea is to help water drain away and not stand on this edge or even funnel into the gap. Tops of gates are often slightly sloped as well so water doesn’t stand on them.


Rather than drainage holes, what about sealing it with silicone? I m curious because I bought an 18th century panel made of approx. 5/16” metal bent into a fairly complex mesh pattern. I m going to be using it in the center of a gate similar to the OP s. I haven t begun construction, but how to deal with the groove it will sit in on the bottom rail is a concern. I m not trying to hijack the thread, since whatever solution works for one will work for the other.

Opinions?

- Rich

I don’t think there is ever a good way to seal external wood, water tight. Water always seems to find a way in. And the way the wood expands and contracts makes it so hard to keep a seal. I think if you try to seal it, water will get in, and then the sealant will just make it take that much longer to dry out.

I do think there is value trying to seal the top of a structure, to shed as much water as possible. But something like this near the bottom, where water could collect, I think it’s best to figure out how to get the water out as easy as possible.

-- Clin

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bd1886

34 posts in 326 days


#9 posted 07-09-2018 01:37 AM



Pics helped a lot, but I still have a few questions. If I understand this correctly, the frame is made up of a pressure treated center and 1/2” ceder on the outside of that. The ceder overlaps the PT wood such that it forms the grove that traps the panels boards. The panel boards will be vertical?

If I have this correct, I agree with Aj2. Put a single fastener in the center of each board. I recommend a stainless steel brad. Stainless won t rust and therefore won t react with the tannin in the wood and make black streaks. An alternative would be stainless or brass screws. But, on the back side of the gate, you can just shoot a brad in at an angle. It will be so small it will be unnoticeable.

NO GLUE, on the panels boards anywhere. The exception would be to not use a fastener and just put a dab of glue in the center of each board.

This will allow each board to expand and contract from its center. The boards need to be spaced far enough apart that when they swell, due to rain etc., they will not push against each other too much (best if not at all).

If you need the gate to be solid (no gaps you can see through), you can tongue and groove the panel boards. Then when you install them, put some space between them to allow for expansion. Meaning don t push the boards tightly together. Especially if they are known to be dry. For example, an 1/8” gap. The T&G will keep the gap from opening all the way through, as long as the T&G is deep enough.

It is possible to not even use a fastener in the boards and just allow them to float. The problem with this is any gap or tongue and groove spacing is not likely to be evenly distributed. So unless your T&G were unusually deep, a gap all the way through the boards could show.

I just found this wood shrinkage/expansion estimator. You can look up the temperature and relative humidity data for your area and plug it in. You want to look at seasonal, NOT daily temperature and humidity.

http://owic.oregonstate.edu/wood-shrinkswell-estimator

In any case, 2% movement is realistic. Assuming a 40” wide gate, that s over 3/4” of total expansion and contraction.

Water will collect in the bottom frame member due to the groove that traps the boards. This is where I would put weep holes. Just drill 1/4” – 3/8” or so holes through the bottom of this. I ve spaced these about 6” apart and used a chisel to slope the bottom of the groove towards the holes. This slope probably doesn t do much of anything. Just don t make the holes so large or frequent that they reduce the strength of the frame significantly.

They can t be seen since they are on the bottom edge of the gate. That way, any bulk water can drain out. I live in a very dry climate, and I had an existing gate on my house that did not allow for this drainage. And it all rotted out in less than 10 years. We get 6” a year or so of total rain. Like I said, dry.

Remember, even rot resistance woods like ceder or PT, are just that resistant. So anything you can do to reduce the amount of time it is exposed to water, the better.

FYI, an alternative is to make the bottom a tongue and grove where the groove is in the ends of the panel board and the tongue on the frame. This way there is no place for water to collect. In your case, this would require the PT wood to stick out from the ceder and be cut to form the tongue.

Something to consider doing is to putting a slight slope on the top edge of your bottom ceder panels. The idea is to help water drain away and not stand on this edge or even funnel into the gap. Tops of gates are often slightly sloped as well so water doesn t stand on them.

Rather than drainage holes, what about sealing it with silicone? I m curious because I bought an 18th century panel made of approx. 5/16” metal bent into a fairly complex mesh pattern. I m going to be using it in the center of a gate similar to the OP s. I haven t begun construction, but how to deal with the groove it will sit in on the bottom rail is a concern. I m not trying to hijack the thread, since whatever solution works for one will work for the other.

Opinions?

- Rich

I don t think there is ever a good way to seal external wood, water tight. Water always seems to find a way in. And the way the wood expands and contracts makes it so hard to keep a seal. I think if you try to seal it, water will get in, and then the sealant will just make it take that much longer to dry out.

I do think there is value trying to seal the top of a structure, to shed as much water as possible. But something like this near the bottom, where water could collect, I think it s best to figure out how to get the water out as easy as possible.

- clin

No T and G. (Believe you me…..if I’d of had the bits they’d a been used.) I did offset the front and back slats so no light will show through though.
Using coated torx deck screws as fasteners on the whole thing and by the time I get done with a few wormholes, wear spots through the “aged” penetrating fence oils and a few faux joinery plugs? Should look cool. (I’ll post pics.)

This is all real helpful advice and will keep it all in mind for future exterior projects. Thanks much! Scott

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clin

1027 posts in 1359 days


#10 posted 07-09-2018 02:05 AM

FYI, easy to make T&G with a table saw. But, I get that’s not what you’re doing on this project.

-- Clin

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bd1886

34 posts in 326 days


#11 posted 07-09-2018 02:27 AM


FYI, easy to make T&G with a table saw. But, I get that s not what you re doing on this project.

- clin

I did think about that after realizing the error of my ways and having the face routering done. So…..silk purse out of a sow’s ear time I’ve decided. (Once I get done it’ll all “work” cosmetically “ and “structurally” now.)
Spent a huge chunk of my 40 year career making the aging out of surfaces look custom or making all carpenters look equal…..now it’s just time to cover my own butt and fun stuff this sawdust worship thang! (Feels real good to be getting back into it after a ten year break white collar.) My knowledge is fairly extensive but has holes because of learning from finish and restoration backwards but it truly was good learning none the less. Thank you for helping it all continue! Scott

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bd1886

34 posts in 326 days


#12 posted 07-09-2018 04:00 AM

Used that calculator and swelling will be substantial enough to insure the tact of keeping those central panel boards free as possible. Will take the stainless brad nail approach plus minor inset flashing at the bottom. (It will give me a good excuse to put a very small chamfered ledge on that bottom rail top.)

Appreciate your direction to that calculator! Scott

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bd1886

34 posts in 326 days


#13 posted 07-14-2018 01:33 AM

Here it is done except fo mounting and adding small capitols at the top of the styles. (Large ones on top are for the fence posts and will make 2 smaller/thinner rectangular ones for the gate itself.)
Also: Going to shear the bottom ledge (hides flashing and drainage channels) back a bit.

Thanks for the advise and help! Scott

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