Heard On the Forums

Editor’s note: In this issue of PDB, we’re running excerpts from our forums in place of letters from readers. That’s not because we didn’t receive any good letters or e-mails — we didn’t receive any at all! We aren’t kidding when we say we want your two cents. E-mail us at prodeck@hanleywood.com or mail letters to Professional Deck Builder, 186 Allen Brook Lane, Williston, VT 05495.

Gap Between Siding and Beams?

Posted by: roberthathaway

On a freestanding deck where the beams will be perpendicular to the house, should I leave a gap between the aluminum siding and the end of the beam? I am worried about thermal expansion and corrosion with the pressure-treated lumber contacting the aluminum. Last, has anyone dipped the hardware in, say a Cabot Australian Timber Oil sealer prior to installation?

Posted by: ArtDeck-O

In today’s treatment processes, the copper content has been reduced to the point that it’s not that much of an issue. Whether you use Micro ACQ or MCQ, your hardware should be okay. I’d mount the beam at least 1 inch from the house so it can dry.

Posted by: Mike K

ArtDeckO is correct that they have reduced the copper in the treatment process to reduce corrosion issues with fasteners. That said, it is a good idea to use stainless steel hardware and fasteners or at least high-quality hot-dipped galvanized. There is really no need for additional treatment from there. As far as spacing the beam from the house, most expansion with lumber will be relative to moisture versus thermal. Leaving a 1- to 1 1/2-inch gap would suffice.

Decking With Tongue-and-Groove Ipe

Posted by: kidrok

Has anyone installed ipe tongue-and-groove lumber in an uncovered area? If so, are there things to watch out for?

Posted by: Redwood:

Yes I have, once. I would only try it if the deck was well ventilated. We had some slight cupping problems. We sanded it down with a floor sander and there have not been any issues since. That said, I would not encourage it.

Posted by: Mike K

I sell large quantities of T&G ipe and recommend it for covered applications only, after seeing some of the results and dealing with unhappy contractors and homeowners when installed on open decks. Even though ipe is a fairly stable product there is some movement due to moisture. Where exposed to soaking rains, ipe can expand enough across an entire deck to push the end pieces off the framing.

Posted by: John Hyatt

I have done several ipe T&G 1x6 projects with no problems at all including my own hot tub–area floor. I let that set out in the weather 2 years before I put the building on it.

T&G decking drains the same way as square edge material — through the gap. Putting it down tight like an inside floor will cause the movement you all are talking about.

My supplier, East Teak, is a full service mill. I have them add 1/8 inch in the groove and bevel both sides. I install with SS screws through the tongue and construction adhesive, and I cut a 1/2-inch slot in the tongue every 3 feet or so for drainage. I leave a 1/16-inch gap between boards. The slot and the screw don’t show. The frame has got to be secure with no over spans and cross ventilation below is a must.

Posted by: Lavrans

Anything that’s going to hold the moisture in is going to accelerate the demise of that decking. A 1/16-inch gap is going to hold a lot of dirt, and the dirt is going to hold the moisture. Around here in the Pacific Northwest, that small a space cuts a deck’s life in half.