Homosote

Just screw. You'll be glad you did. Dave

I screwed it down, I used lots of screws, especially along any edges.

Unless you use 2000 screws per foot I would suggest glue and screw     Like DK said humidity will make the homasote do crazy things

I've always used screws. Similar to John's photo.

Thank you guys!

I used drywall screws. I suggest a minimal amount of screws to reduce sound conduction between the Homasote and the plywood. In some places I have screws at 3 foot intervals, but in other places at 1 foot intervals. You just have to play-it-by-ear to use enough screws to achieve a level surface. You can always add screws later.

@Bruce Brown posted:

I suggest a minimal amount of screws to reduce sound conduction between the Homasote and the plywood.

I don't see any  issue with sound conduction with lots of screws.  Truthfully, the bigger issue IMO is the vibration of the panels together making noise.  My goal was to make sure the sound deadening qualities of the Homasote were fully utilized, and the results seem to have proven that out.  Of course, @Tom Tee, a guy with WAY more experience than I have recommended a LOT of screws, I took his advice.

@gunrunnerjohn posted:

I don't see any  issue with sound conduction with lots of screws.  Truthfully, the bigger issue IMO is the vibration of the panels together making noise.  My goal was to make sure the sound deadening qualities of the Homasote were fully utilized, and the results seem to have proven that out.  Of course, @Tom Tee, a guy with WAY more experience than I have recommended a LOT of screws, I took his advice.

Good point!  One that seems rarely made, too. The elimination of vibration which in turn eliminates propagation of sound is what's important.  Assembly of my layout was all glued and screwed in place to make everything one unit.

We screwed it down about a foot apart. No problems and 20+ sheets.

Glad that we didn’t add glue as we have moved some around, cut holes, pits, etc.

@Bill Webb posted:

We screwed it down about a foot apart. No problems and 20+ sheets.

Glad that we didn’t add glue as we have moved some around, cut holes, pits, etc.

Exactly my reasoning as well, I didn't want to deal with the glue when the inevitable changes came along.

I screwed mine down. One advantage not mentioned is if down the road you plan on structures. After you build them. It’s sometimes easier to scenic around them if your adding a lot of details at the workbench on a plywood base. When it comes time to place the scenic base on the layout. You can cut the area the base will reside in with a utility knife. This way the structure can reside at ground level. Screw it in place and add more screws around where you cut the hole. Fill the seem in and continue scenicing.

I have been using Homasote for about 40 years on my layouts. I always use carpenters wood glue, then use widely spaced sheetrock screws to hold everything down tight until the glue set up. I especially use screws along any edges, and on any "heaved up" or "bubbled" areas in the center of large pieces. Back in my "cheap" days, I later removed the screws so I could use them over again. On the last 2 or 3 layouts, I just leave the screws in as it is not worth the time to save them.

Jeff

I just screwed mine done and I used about 15 sheets and no problems and this is my second layout. When we moved I took down the old and salvaged the Homasote from it and reused it on the current layout. Advantage to not glueing it done. Both of mine were in basements and never had a problem and the first one was up 20 plus years.

I am posting a contrarian approach to Homosote.  I like and use Homosote, but I did not put plywood under it as usually recommended.  I built a layout in the 1980s before forums and I read about Homosote in MR, but not the practice of putting plywood under, so I built the layout with the Homosote directly on the bench structure with no plywood from lack of knowledge.  Did not use glue, but screwed down probably on one foot center (cant remember for sure).  This was in an attic subject to extreme heat and humidity variation, which theoretically is a recipe for disaster with what I did.  The layout was up for two decades without any problem no warpage no change.  It worked great for decades.  I posted this on this forum years ago and people said I was lucky and this was a bad plan.

Two things contribute, I think.  Bench modules were 8’ by 30” (I think), but I did put supports across the 30” on 16” or 24” centers and I did screw down to these cross members too, not just the perimeter.   The key thing however is that I painted the Homosote.  Top side green finish paint, bottom sealed with old junk paint.  I was careful to paint the edges. I think this kept the humidity from warping it (along with screws) and gave a finished appearance to the final layout.  Thinking about doing it again on my next layout because it worked.

YMMV

Shields up; incoming fire

Bill

I screwed my homasote down to the plywood underneath.  I used a decent amount(maybe one every 10-12 inches) of screws but I would recommend using more, probably something like John did especially on the edges to keep things level. 

I'm with ogaugenut: I also use homasote screwed directly onto an open frame of joists, with no plywood. Plenty strong enough--I crawl on them all the time. I have two sections of table that my dad had made in 1957. I have a tradition of starting every new layout with them. After more than 60 years, they are still in great shape.

I've built 4 layouts and on the last 3 I glued it down with a lot of wood glue.  I used the other sheets as weight on top of the glued sheet and let the glue dry for a few hours.  I also used cork roadbed on top of the homasote and I attached that with silicone caulk.  That approach made less of a sounding board.  In over 20 years I never had the homasote separate from the plywood.