+- Woodnet Forums (https://forums.woodnet.net)
+-- Thread: adhesive for outdoor firring strips (/showthread.php?tid=7378415)
adhesive for outdoor firring strips - thewalnutguy - 04-27-2025
[attachment=54469][attachment=54470]I'll be replacing the cedar siding that was applied when the huse was built 53 years ago that's showing signs of age. Being wood, it's also been walking the nails out with expansion and contraction from weather conditions. I plan to have the new siding extended over several feet of concrete block foundation. This will require two inch firring strips applied to the blocks with styrofoam backing between the firing strips spaced sixteen inches apart. The siding company has recommended use of pressure treated lumber for the firring strips.
I'd purchased some "3/4 X 4 treated material, cut to four foot lengths and planed to half inch thickness. I ran a zig-zag bead of Liquid Nails adhesive between the thin material and 2X4. Applied two F-style clamps and ran about a dozen screws for evan clamping pressure, and let them cure for two days. Today I removed the clamps and started removing the screws. And as soon as I removed the first screw the 1/2" material started to curl away from the 2X4. The thinner material let go of the 2X4 as soon as the last screw was removed. Some of the Liquid Nails stayed with the 2X4, the rest came with the 1/2" material. Much of the adhesive could be removed by fingers, a small amount required a scraper. The adhesive that came free on its own left nothing behind other than a shadow from the moisture.
Now I'm wondering if the lack of adhesive is typical of pressure treated lumber, or simply that it's high moisture content. I could go with Titebond water proof glue between the two layers of treated lumber. I'm concerned, however, about the bond between lumber and the cement blocks. The plans are for a good bead of adhesive and two Tapcon screws. The longest firring strip will be about three feet. Liquid Nails seems to be the flavor offered by most retailers, but is there a different adhesive that would be preferred. I'd like the firring strips-to-blocks to be a permanent marriage.
RE: adhesive for outdoor firring strips - MstrCarpenter - 04-27-2025
First of all, I would skip the glue; no need for it. Tack the 1/2" to the back of the 1-1/2" so it's basically just a spacer. Now this is just me, but I would skip the Tapcons too. My "go to" way to fasten anything to concrete is to use ceramic coated deck screws and a zip tie. This is actually just a modern way to do the same thing craftsmen have been doing for hundreds of years. They'd drill a hole with a star bit and add a piece of wire before driving a nail. A step better was copper wire and a screw. I changed to plastic because it would melt and stick to the concrete. The only trick is don't be bashful when driving the screw; run it right in. This was a discovery when using Tapcons to furr out a con'ct. wall for drywall. The Tapcons had a failure rate just barely low enough to keep trying. When they stripped out the only thing handy was plastic coffee stirrers. The rest is history, and those blue screws have been added to the list of items I have no *#&%@ use for.
RE: adhesive for outdoor firring strips - fredhargis - 04-29-2025
I'm betting the adhesive problem is due to the moisture in the treated wood. I'm not sure there is an adhesive I would trust with the wet wood, it needs to be dry.
RE: adhesive for outdoor firring strips - Gary G™ - 04-29-2025
I would try Lexel. I used their waterproof adhesive and it’s been great.
They advise it can take a week to fully cure.