One type of underfloor
23 September 2006
Explained in another post using the correct underlayment (with floating installation method) has to be the start of your enjoyment of the end result.
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HI,
I am planning to lay an oak floating floor in front and back room of my terraced house, the 2 rooms are connected by double doors. one is concrete floor, the other has floor boards (terrace is built on a hillside). You suggested using ply or OSB glued/nailed down, and then foam or rubber underlay, but didn't mention any DPM. Won't the concrete area require a DPM? Also, could I use Fibreboard instead of ply or OSB?
Many Thanks,
Dave.
Posted by: Dave | 20 July 2008 at 10:17 PM
Hi Dave, welcome
You'll have to use either plywood or OSB, the fibreboard is an underlayment and not a stable or suitable subfloor.
And no, when you glue or screw ply of OSB to the concrete floor you don't need an extra dpm.
Wood You Like Ltd
Posted by: Karin H. | 21 July 2008 at 09:01 AM
Is this the case with engineered floors too?
And the size of ply, can i not lay sheets of 8x4?
Posted by: Paul | 08 August 2008 at 06:25 PM
Hi Paul
Yes, wood-engineered flooring is all wood too (be it in a combination of wood-types).
If you lay very large sheets your subfloor could echo due to unevenesses in the underfloor. And trust me, smaller sheets are much more 'handy' to work with.
Wood You Like Ltd
Posted by: Karin H. | 09 August 2008 at 09:09 AM
We recently removed a ceramic tiled floor which was defective to find that it had been laid directly onto green, 25mm floor grade, chipboard. The chipboard is a floating floor and is in 2400 x 600mm boards underwhich is approx 50mm polysterene then a damp proof membrane. Having scrapped most of the remaining adhesive from the chipboard, can an engineered board be put down on top and if so, what preparation? I know ideally it would make sense to remove the chipboard altogether but we are talking around a 120 metres/2 and all the stud walls are built over it and compounding the problem we would have to seek LB consent to remove and replace any internal studwork, so best avoided.
Julie
Posted by: julie2933 | 18 August 2008 at 01:08 PM
Dear Julie
If the chipboard subfloor is stable and sound you can install the wood-engineered boards using the floating method. All you have to add is 3mm foam underlayment between chipboards and wood floor and glue all T&G's correctly.
Hope this helps
Wood You Like Ltd
Posted by: Karin H. | 18 August 2008 at 02:04 PM
Can I ask if this can be laid straight down on timber joists at first floor level, or do i need a subfloor of particleboard?
Posted by: Craig Stephenson | 25 September 2008 at 12:04 AM
Hi Craig
Yes you can as long as:
your new floorboards are load-bearing (18m thick at least)
the new floorboards connect with at least 3 joists
and the joists should not be further apart than 35 - 40 cm
Wood You Like Ltd
Posted by: Karin H. | 25 September 2008 at 09:00 AM
Hello experts Help required,
My son has recently purchased a house built in the 1950's, and the downstairs rooms and hall have oak parquet flooring. In places the blocks have lifted and underneath there appears to be a 2" layer of a soft powdfwery substance like plaster on what appears to be stable concrete. Does anyone know what this layer on the concrete is? Is it an insulating layer, and how can I repair it to obtain a level sufrace to refit the oak blocks to? Thanks, Steve.
Posted by: Steve Rowland | 02 November 2009 at 12:27 PM
Hi Steve
We've never encountered this and will "ask around" for you and your son. Are you sure it is not deteriorated chipboard?
Wood You Like Ltd
Posted by: Karin H. | 02 November 2009 at 01:03 PM
Hi there,
I want to fit a Floating style solid brushed & oiled floor in a house with Two types of sub-floor (Floorboards & concrete screed)But as the floorboards sit 4mm lower than the concrete I was hoping to put a DPM (vinyl sheet)on the screed and then a 2mm foam underlay: To build up the floorboards a DPM again to prevent moisture from below and then a 6mm fibreboard underlay. Then I wanted to lay the boards by gluing the toungues all sides. I am aware of the idea of ply boarding the whole area and forgoing the DPM but have limited ceiling height and am working in a grade II terraced house,So don't want to raise the floor any more than necessary! Is it a lost cause or can it work like this???
Posted by: Carl | 10 December 2009 at 07:40 PM
Hi Carl
Do not place a DPM over your existing floorboards no matter what. This will prevent the normal and necessary ventilation and could cause rotting joists etc.
Also I don't think 2mm foam (especially not the one more suited for laminated floors) is sufficient. 3 or 4mm would be better. The fibreboards tend to create a wobbly floor, so best would be to create a level underfloor first, perhaps with hardboard/plywood of various thickness and then lay a 3mm underlayment over the whole.
Hope this helps
Wood You Like Ltd
Posted by: Karin H. | 11 December 2009 at 08:55 AM
I want to fit a floating (but glued tonue and grove)solid oak floor on two different surfaces (concrete and wooden floor boards). The concrete floor surface is 3mm lower than the floor boards. I have noted the other comments on the page, but wonder if I have to place ply over the wooden floor boards as well as the concrete? The surfaces were in two rooms that have now been knocked through into one, so the same ambient temperature will be in the room. What do you suggest?
Posted by: Steve | 20 February 2010 at 11:05 PM
Hi Steve
It mainly depends on the direction of your new boards over the existing floorboards: if perpendicular then glueing 3mm hardboard sheets to the concrete would be sufficient to create one type of underfloor. The flexible adhesive you use for the hardboard sheets will act as a moist repellent.
Then on top of the hardboard sheets you lay foam underlayment (without DPM) and install your wooden floor. Do read this article on solid wood floors too:
Solid Floors - what to note
If however the new boards will be installed in the same direction as the existing floorboards it is always better anyway to board over the existing floor to prevent draft and extra movement, especially when the existing floorboards are a bit uneven (see-saw effect).
You could nail/staple 3mm hardboard sheets on the floorboards and 6mm hardboard (or 2 x 3mm) over the concrete (glueing).
Hope this helps
Kind Regards
Wood You Like Ltd
Posted by: Wood You Like Ltd | 21 February 2010 at 11:55 AM
Hello , Hope you can help me ?
Ive just bought a new solid 120mm wide 18mm thick wooden floor to be fitted in the kitchen/dining room and the sub floor is concrete what would be the best way to fit the wooden floor?
Posted by: lee duckworth | 27 March 2010 at 07:03 PM
Hi Lee
Thank you for your question. Question for you in return: does your floor come in so-called random length, for instance the known 300 - 1200mm? If so, you first have to check how many very short lengths are in a box. If too many than it is not advisable to install such a floor using the floating method and it would be better to fully bond the floor with flexible adhesive to the level and dry concrete floor.
See this article about the short end of the stick/board.
Solid Floors - what to note
Hope this helps
Wood You Like Ltd
Posted by: Wood You Like Ltd | 28 March 2010 at 12:50 PM
Hi
I have a similar question to Julie above except although stable the chip board sub floor is shapped like a puddle. Its max difference is 18mm between the bottom in the centre of the room and the edges. Average puddle to fill 12 - 15mm if that makes sense over a room 4m * 4m. I intend to lay eng oak with a 3 or 4 mm underlay.
I was going to use a 2 part latex self leveling compound however I am having second thoughts. My question is will a 2 part latex self leveling stuff do the job or do you recommend something else?
Thank you
Andrew
Posted by: A Robson | 21 November 2010 at 05:03 PM
Hi Andrew
In your case I would definitely fix the underfloor a different way. chipboard is a rubbish product, and could have sagged causing this problem.
IMHO the best solution would be to rip out the chipboard and replace with 18mm WBP Plywood.
Hope this helps
Kind Regards
Wood You Like Ltd
Posted by: Karin H. | 24 November 2010 at 01:25 PM