Float or glue engineered flooring over chipboard with UFH

[gOBO81]

Our extension build is nearing completion and it's time to lay the flooring; around 60m2.

 

It is a suspended timber joist floor with spreader plates and wet UFH piping throughout. Laid on top of the joists is 18mm chipboard.

 

We have selected to lay a 14mm engineered flooring (3mm oak top layer). We would prefer to have this glued down but our builder has suggested it would likely have to be floated due to the UFH expansion/contraction.

 

I am struggling to find clear guidance on glueing down as most guidance appears to presume where there is UFH it is screeded, but we have a suspended floor.

 

If anyone could offer any advice it would be greatly appreciated.

 

Cheers

[Mr Punter]

Glued will feel more solid but either will do.  Either way, leave a decent expansion gap around the perimeter.

[JohnMo]

13 minutes ago, gOBO81 said:

am struggling to find clear guidance

Flooring manufacturer instructions normally give explicit instructions. Ours had to be glued down on top of UFH. Doesn't mean yours will. If in doubt ask the supplier.

 

 

 

 

[joe90]

49 minutes ago, Mr Punter said:

Glued will feel more solid but either will do.  Either way, leave a decent expansion gap around the perimeter.

+1, I hate floating floors. Plus the glue will help transfer the heat better.

[gOBO81]

3 minutes ago, joe90 said:

+1, I hate floating floors. Plus the glue will help transfer the heat better.

Likewise, hence it being our preferred method. 

 

Is there a particular glue that is preferred for adhering to chipboard floors? I presume it would need to be flexible? 

[joe90]

The flooring supplier usually recommend/stipulate the best adhesive (ours did).

[Mr Punter]

28 minutes ago, gOBO81 said:

Is there a particular glue that is preferred for adhering to chipboard floors? I presume it would need to be flexible? 

 

It is very expensive.  Essential that the subfloor is completely dust free, which is difficult to maintain unless you do the cutting remotely or with a posh Festool thing.

[joe90]

10 minutes ago, Mr Punter said:

 

It is very expensive.  Essential that the subfloor is completely dust free, which is difficult to maintain unless you do the cutting remotely or with a posh Festool thing.

Yes my glue (can’t remember the  type) was pricey. Also I vacuumed each bit of floor just before laying down the glue to make sure it was dust free.

[Gus Potter]

1 hour ago, gOBO81 said:

Our extension build is nearing completion and it's time to lay the flooring; around 60m2.

 

It is a suspended timber joist floor with spreader plates and wet UFH piping throughout. Laid on top of the joists is 18mm chipboard.

 

We have selected to lay a 14mm engineered flooring (3mm oak top layer). We would prefer to have this glued down but our builder has suggested it would likely have to be floated due to the UFH expansion/contraction.

 

I am struggling to find clear guidance on glueing down as most guidance appears to presume where there is UFH it is screeded, but we have a suspended floor.

 

If anyone could offer any advice it would be greatly appreciated.

It's a dilemma!

 

Over the years I've done a few UF systems and each time I learn something new, improve where I can and adapt the design the based on my learning and what new on the market.

 

The house we have at the moment is a 1955 house with suspended floors. We took the back off it and extended out to form an open plan space. The extension is a concrete slab on PIR on grade. But the floor levels in the existing house vary and as they are now forming part of the open plan space we have a mix of materials forming the floor. Timber / concrete and a level variation.. it's small but it is there. Also the existing house solum is sealed with tar and a bit compromised in places thus we have different moisture levels.

 

All of the above results in movement between winter and summer which is noticeable.. if you are inclined that way to have these thoughts. For this house I floated the engineered flooring on a 2.0mm thick layer of foam, just the bog standard stuff. If you jump about on the floor you are aware that the different parts feel more solid than others. But again I'm always "monitoring! most folk wonder if I'm ill when I mention. Now fair enough the foam insulates and makes the UF less quick to respond. In the odd spot where the floor levels were a bit off locally I added some extra strips of foam as a packer. But we have lots of rugs and so on which do insulate the floor much more so than a thin layer of foam. If you lift a rug the floor is much hotter under.

 

We have a bathroom on a supsended joisted floor. The tiles are these large format ones. The UF pipes are in a screed on PIR between the old house joists, no spreader plates. A while ago I posted about this and @nod as always provided some great advice. I followed it and sure enough after almost two heating seasonal cycles no cracks in the tiles. Thanks @nod! The main thing was the use of a decoupling matt. When I first started messing about with UF these products were not available.. mind you neither were large format tiles available to the DIY market at an affordable price.

 

Now when you read the fine print of the flooring suppliers you nearly always breach their T & C's in terms of what you need to comply with. One it the temperature range. Where you have UF pipe conjestion the floor can get quite hot at times cf other areas. I just accepted that is was nearly impossible to comply for our house so took a pragmatic risk based approach.

 

In summary I did think about glue the floor down. But then I though what happens if I get a leak in the kitchen sink say . Lifting any damage glued down flooring could be a nightmare! We have had a plant pot that leaked water and did not spot. Some minor damage has occurred but I know I can easily fix the floor if need be.

 

 

 

 

 

 

 

[nod]

2 hours ago, Gus Potter said:

It's a dilemma!

 

Over the years I've done a few UF systems and each time I learn something new, improve where I can and adapt the design the based on my learning and what new on the market.

 

The house we have at the moment is a 1955 house with suspended floors. We took the back off it and extended out to form an open plan space. The extension is a concrete slab on PIR on grade. But the floor levels in the existing house vary and as they are now forming part of the open plan space we have a mix of materials forming the floor. Timber / concrete and a level variation.. it's small but it is there. Also the existing house solum is sealed with tar and a bit compromised in places thus we have different moisture levels.

 

All of the above results in movement between winter and summer which is noticeable.. if you are inclined that way to have these thoughts. For this house I floated the engineered flooring on a 2.0mm thick layer of foam, just the bog standard stuff. If you jump about on the floor you are aware that the different parts feel more solid than others. But again I'm always "monitoring! most folk wonder if I'm ill when I mention. Now fair enough the foam insulates and makes the UF less quick to respond. In the odd spot where the floor levels were a bit off locally I added some extra strips of foam as a packer. But we have lots of rugs and so on which do insulate the floor much more so than a thin layer of foam. If you lift a rug the floor is much hotter under.

 

We have a bathroom on a supsended joisted floor. The tiles are these large format ones. The UF pipes are in a screed on PIR between the old house joists, no spreader plates. A while ago I posted about this and @nod as always provided some great advice. I followed it and sure enough after almost two heating seasonal cycles no cracks in the tiles. Thanks @nod! The main thing was the use of a decoupling matt. When I first started messing about with UF these products were not available.. mind you neither were large format tiles available to the DIY market at an affordable price.

 

Now when you read the fine print of the flooring suppliers you nearly always breach their T & C's in terms of what you need to comply with. One it the temperature range. Where you have UF pipe conjestion the floor can get quite hot at times cf other areas. I just accepted that is was nearly impossible to comply for our house so took a pragmatic risk based approach.

 

In summary I did think about glue the floor down. But then I though what happens if I get a leak in the kitchen sink say . Lifting any damage glued down flooring could be a nightmare! We have had a plant pot that leaked water and did not spot. Some minor damage has occurred but I know I can easily fix the floor if need be.

 

 

 

 

 

 

 

Your welcome 

[Gus Potter]

2 minutes ago, nod said:

Your welcome 

I'll post a photo at some point so you can see where you advice was implemented! Thanks again. Do you want to come up and work in the Glasgow area?