Wood board between mattress and steel frame

Hi all, first time posting,
I want my mattress to feel as firm as possible. I have a pragma size foundation. They are 2 frames attached with a few bolts. I replaced my
saggy foam GhostBed with an extra a BeautyRest silver extra firm spring mattress. IMO this foundation has a few issues:
-most of the contact points are wires (4-ish mm), which definitely digs into the bottom foam layer more than typical 30-75mm slats
-the square bars are solid but the wires have some flex to them,
-the bars that make direct contact with the mattress seem to be a tiny bit higher than the wires
-there are one sqaure inch steel plates welded directly over the 4 middle legs of the frame, about ¼" to ½" thick. The creates a bump in the center of the mattress.

It seems like using plywood between the mattress and frame would help keep the mattress firm and flat. I’ve read here that 1.5" of plywood is recommended if used instead of slats, that would be prohibitively expensive (I can’t use pine). Since I want to firm up a foundation can already support a mattress, couldn’t I use 3/16" (5mm) plywood instead. It would be 1/8 the price and 1/8 the weight
Cut into four 20" planks to run horizontally for ventilation and prevent cracking, with notches cut out over the bumps over the center legs. I don’t use the “adjustable” feature anyway, Is there any reason
potential issues? Is it a pointless thing to do? Could it do more harm than good?

TLDR: Is there any reason I should but 5mm plywood between a spring mattress and steel wire platform foundation?

Hi WalterMelon.

Welcome to our Mattress Forum! :slight_smile:

[quote]It seems like using plywood between the mattress and frame would help keep the mattress firm and flat. I’ve read here that 1.5" of plywood is recommended if used instead of slats, that would be prohibitively expensive (I can’t use pine). Since I want to firm up a foundation can already support a mattress, couldn’t I use 3/16" (5mm) plywood instead. It would be 1/8 the price and 1/8 the weight
Cut into four 20" planks to run horizontally for ventilation and prevent cracking, with notches cut out over the bumps over the center legs. I don’t use the “adjustable” feature anyway, Is there any reason
potential issues? Is it a pointless thing to do? Could it do more harm than good?[/quote]

Good thinking with notches cut out over “bumps over the center legs” (maybe even over the adjusting brackets) this helps with the top and bottom ply strips shifting. The dual frame has center support lengthwise and across (12 legs all in all) so the flex wouldn’t be that much. Any thickness added between the mattress and steel frames will help with the sag and redistribute to a certain extent the weight of the mattress and people sleeping on it. Ply thickness is a factor of course … the 3/16" piece ply won’t be too flexible if it is hardwood (birch, poplar, or maple according to our master craftsman. If you are US based he recommends this one from PureBond-Birch-Plywood-from Home Depot or similar.

One thing to keep in mind is the possibility of the ply shifting during the course of the night. (especially the ones without the notches.) I don’t think that condensation is an issue with a spring mattress, but for an all-foam mattress, the ply will absorb any moisture or condensation which can encourage mold and mildew, so our master craftsman (who experimented in the past with a similar setup) advised sealing it with a low VOC water-based varnish.

Overall it sounds like a good plan
Phoenix

It furniture grade poplar (I’m allergic to pine sap,) Notches keep the middle from shifting, top and bottom are bolted to the frame (has bolt holes head/foot board attachments). Looks flat, walked around on it before putting the mattress on, didn’t crack or warp. BUT all of its issues feel worse. The area where the two frames meet feet much firmer with the wood in place. And, astoundingly, the center bump is raised enough to be visible from the top of the mattress. Im 100% sure there is no wood over the bumps, climbed under to confirm, the sqaure in the middle has 1.5" clearance on all 4 sides.

I put a 3" latex topper over the mattress. The difference got bigger not smaller.

This foundation still has hundreds of reviews online, no one has ever mentioned these bumps. I’m dumfounded.

Hi WalterMelon.

Could you take some photos of the setup from the revealing angles? (without latex, and then with latex) Do you have a Torpedo Level to check what’s going on by placing it in strategic points on the system? (include that in the photo)
I’ll ask our master craftsman to have a look at it and see if he can spot any issues.

In theory, if the frame design & construction is faulty there should be some sign of it on www … is It may be that there is some defect in this particular metal frame. Is it still in the returning period? You may want to contact the manufacturer with some of the photos and see what they have to say.

Phoenix