floating solid wooden floor bouncing

[willitwork]

i have recently installed a floating floor made of solid maple in the living room and hall. i put down plastic sheet and foam underlay. i have allowed 3/4 inch expansion gaps by walls. the hall looks excellent but i have a 1 meter square patch in the living room that bounces when walked on. it is not particularly noticeable when walking but when you see someone else walk on this patch it is very noticeable. any ideas on why this could be and more importantly how to solve it?????

 

[WoodYouLike]

Most obvious reason is a dip in your underfloor.

To solve it would be to try to add some thin underlayment under the floor where the floor dips (be careful as to where to place this, wrong placing could result in bouncing effect somewhere else).

Preventing this problem (which occurs frequently -specially in new build houses, new screed/concrete floors) is to go over the underfloor with a kind of spirit level (straight batten) to find any dips beforehand and/or walking over the partly installed floor to 'feel' any movement (or have someone else look at any possible 'bouncing movement).

 

[willitwork]

the under floor is concrete and i have glued the boards together so i cannot remove the boards to insert more underlay.
would screwing one board down the to concrete floor help or could this make it worse.
would placing a heavy weight over the area for some time have any effect or would it just return to the original state when removed.

 

[WoodYouLike]

the under floor is concrete and i have glued the boards together so i cannot remove the boards to insert more underlay.
would screwing one board down the to concrete floor help or could this make it worse.

NEVER screw a wooden board to the underfloor, this will prevent any normal seasonal movement.

would placing a heavy weight over the area for some time have any effect or would it just return to the original state when removed.

No harm in trying this. The bouncing effect could also reduce after a while, when the recently install floor has had time to settle, but it could also be something you have to learn to live with, I'm afraid.

 

[Pewit]

You could try this solution using expanding foam. It does require you to drill a small hole in the floor but this could be patched up to be amost unoticable.

1. Get a can of expanding foam with a small nozzle (there are two nozzle sizes supplied with some cans)

2. Using a wood bit to fit the nozzle, drill a hole in your floor in the centre of the bouncing are. Then switch to a masonary bit and drill enough into the concrete underneath to insert a raw-plug. Using a suitable screw to fit the raw plug, push the plug down into the concrete and test that it bites as you tighten, then remove the screw.

3. Squirt some water down the hole (to help the foam expand) using a plant spray

4. Place the nozzle in the hole and inject the foam (don't overdo it or your floor may bulge). Then insert the screw and push and tighten to ensure the floor is kept level (using a spirit level) weights may also help.

5. When the foam has dried remove the screw and repair the screw hole using coloured filler to match the floor.

Hope this helps

 

[WoodYouLike]

Like we said before, you have to be very carefully with this method, any extra expanding foam and the whole floor will go.
Plus, it is and will always be foam and after a while it will shrink which will leave you with the same problem again.

Very sorry, but we don't believe in this solution.

 

[willitwork]

i was thinking of the idea of inserting foam myself and trying to bring it level but i thought it would be very difficult to do it well. theres not much room for error.

just one other thing.

the bouncey patch is close to the fireplace,about 1ft from the hearth.
at the fireplace i have run the floor underneath the hearth(still allowing a very small expansion gap inside) . it was a tight fit so the boards are practically touching the underside of the hearth. if they were more free to move would the ripple from the bounce lessen or increase.
i realise this is a difficult one but i said i'd throw it out there.

thanks.

 

[WoodYouLike]

Yes, that might be the case, but you only know if you 'free' them. Anyway it wouldn't harm your floor in the long run, any expansion (and the humidity has been slightly lower than normal this last week) and the boards could start to give you some problems at that place (restricted expansion gap).

 

[Pewit]

Like we said before, you have to be very careful with this method, any extra expanding foam and the whole floor will go.
Plus, it is and will always be foam and after a while it will shrink which will leave you with the same problem again.

Well I have used this solution for my subfloor and it does work - plus you can always inject more foam later (in a different hole) if the floor starts to bounce again.

The consistancy of the expanding foam and foam underlay is not that different and the life of the foam should be 5yrs+ if not exposed to sunlight - the technical data I can find online suggests longer.

But I agree, don't add too much foam initially - best to time youself making a meringue of foam before you start and have some weights availble in addition to the screws to hold it level.

If you're going to have to rip up the floor anyway then the foam injection method is worth trying.

 

[crazyboytoo]

re your bouncing. Is it near enough to the edge to get "Gripfill" into it. This will stop any bouncing. Excellent stuff