Building paper - Sisalkraft 420

[RaceDiagnostics]

I'm looking at getting oak flooring from these guys.

Classic Grade Solid European Oak Flooring

Our Classic Solid Oak Flooring is machined from sustainably-sourced European Oak. The wood has a light biscuit tone and displays a pleasing mix of small open knots (up to 25mm in diameter) and scatterings of pip. The knots can be filled and sanded to a smooth finish if preferred. Some boards...

www.britishhardwoods.co.uk

They recommend puting down this Sisakraft 420 building paper (bitumen coated) onto ground floors, it is expensive on their web site and not widely available, can anyone recomend an alternative?

 

[RaceDiagnostics]

Looks like its A1F BS1521 building paper and is available elsewhere a lot cheaper.

 

[eLuSiVeMiTe]

Solid wood I'd be putting a liquid dpc down then glueing the boards to the screed. Assuming it's not joists?

 

[Ali]

@roofman might know of a product. This was a good watch recently, he actually uses roofing felt but just for levelling purposes. Carpet tiles as underlay is a good idea.

 

[Onoff]

This stuff? Used it in my shed.

 

[RaceDiagnostics]

Its going down over existing pine floorboards.

 

[Ali]

Its going down over existing pine floorboards.

Defo watch that vid then.

 

[RaceDiagnostics]

Luckily my floor is in pretty good condition compared to his. I just plan to give it a sand to take out any high spots.

The bamboo he used is the same as I had laid throughout my old house, the fiters glued it down after finding the hidden nailing could justabout be seen as slight bumps in some lighs as its so hard.

 

[SierraV6]

When I installed bamboo on our first floor (which is boarded unlike the ground floor) I laid 9mm ply and then used a self adhesive underlay from B&Q. Seemingly it’s no longer available but I did find this:

Acoustic Underlay for Solid Wood Floors, Self Adhesive - Identical to Diall : Amazon.co.uk: DIY & Tools

Shop Acoustic Underlay for Solid Wood Floors, Self Adhesive - Identical to Diall. Free delivery on eligible orders of £20 or more.

www.amazon.co.uk

Apparently proper floor layers hate this stuff but I found it quick and easy to use and the floor looks great 8 years on.

 

[Gareth J]

Solid or suspended floor?

If solid, I guess you'll really be needing something breathable so the pine boards don't rot. But equally, if it's solid and there are no draughts to eliminate, are any fancy layers required at all? If I had 20-25mm height to spare, I'd be tempted to take up the old floor and replace it with insulation. If that would even work!

If suspended, are you not going to take up the old boards so you can insulate between the joists? Either way, if that's the case, obviously a draught control layer will be beneficial. However, at this point, I don't see any problem using cheap polythene vapour barrier. Below the vapour barrier moisture is controlled by underfloor ventilation, above the barrier (inc. the new floor) moisture is controlled whatever controls your house humidity? Could be wrong though!

 

[RaceDiagnostics]

Solid or suspended floor?

The floor looks like this, its bone dry underneath.

I have lifted half of the Acasia hardwood flooring that was down, it had no barrier under it.

Once I've finished with the flooring I'll pack in as much insulation between the rafters underneath, but then again the heat lost through the floor probably keeps the pipes from freezing.

 

[dobbslc]

I used bitumen paper I bought from Wickes for £1 a roll!

I have the same sort of suspended wooden floor as you.

 

[RaceDiagnostics]

I used bitumen paper I bought from Wickes for £1 a roll!

I have the same sort of suspended wooden floor as you.

Did you run your new boards at 90degrees or parallel to your old ones, I want to keep mine parallel but also don't want to add extra thickness with plywood sheeting.

 

[dobbslc]

I ran them at 90° to the old floorboards as it is running the full length of the house, I used 6mm ply underneath fixed with 15mm wood screws, (lots of them!) I used Tongue Tite screws in the groves at 45° to fix them down.

 

[dobbslc]

Looks like I got a bargain with that paper! I'm sure the "normal" Wickes price was £8 a roll but I can't find anything close to that now!

 

[Gareth J]

The floor looks like this, its bone dry underneath.

View attachment 315177

I have lifted half of the Acasia hardwood flooring that was down, it had no barrier under it.

View attachment 315178

Once I've finished with the flooring I'll pack in as much insulation between the rafters underneath, but then again the heat lost through the floor probably keeps the pipes from freezing.

In that case, (am presuming the underfloor is properly ventilated) I'd be looking towards a continuous vapour control layer. Keep warm, moist house air out of the floor void and keep cold drafts from the floor void out of the house. Am no expert on this though, there may be a good reason why fancy breathable membranes are required, though I can't think why!

Personally, I reckon kingspan type squares jammed in from above will be a lot easier than fitting from below but yea, that would mean lifting the original floor of course.

I recently did a hallway floor with this method including a cheap, full size vapour control membrane. 75mm kingspan between 100mm joists. More would have been better but it's an unheated area and I was limited to 100mm (actually 90something mm) floor joists for one reason or another.

 

[Keith 66]

Top Tip, If you are using solid wood flooring it is worth stacking it in the room its going to go in for some time, this especially applies if it has been stored poorly.
Years ago i got a job laying a maple floor in a first floor flat, the owner had acquired a load of old stock maple t&g flooring, he had some guys fit it in his living room. It shrank badly & we had to tear the lot up.
Fortunately there was enough still in store to redo the job & rest of the flat, We stacked it in one of the rooms & left it for a month before we laid it to acclimatise & dry out. 9mm ply glued & screwed over the old floorboards & laid the maple over that.
I pity the plumber who has to fix a leaking pipe one day!
In my own kitchen i made access panels to get under the floor!

 

[RaceDiagnostics]

Ok I decided to lay some 9mm ply over the old boards and started looking at plywood. I've heard lots of horror stories about cheap poor quality ply, where is the best place to buy to ensure quality, and what type should I go for? Softwood, hardwood, structural, marine?

 

[RaceDiagnostics]

Any thoughts on which one to go for EN636-2 or EN636-3?

£32 a sheet https://www.mgmtimber.co.uk/9x2440x1220mm-plywood-mlh-en636-2-plymlh849

£52 a sheet https://www.mgmtimber.co.uk/9x2440x1220mm-plywood-performance-en636-3-s-plyper849

 

[RaceDiagnostics]

I eneded up buying this one from Jewson, smarting from the pain at buying 12 sheets.

Eucalyptus Hardwood Plywood FSC 2440 x 1220 x 9mm

This BM Trada Q Mark FSC joinery quality hardwood throughout plywood conforms to EN636-3S and has a phenolic class 3 glueline in accordance with EN314-2. It...

www.jewson.co.uk