Chipboard or floorboards

[MortarThePoint]

I have two areas I am debating what to put down as the floor. One area is above the garage in a home office space and the second is in the attic trusses of the house.

• 22mm Caberdek P5 (~£6/m2), glued along joins and joists and screwed @ 150mm centres along joists
• 21mm softwood plywood (~£10/m2), glued along joins and joists and screwed @ 150mm centres along joists
• 21mm Redwood floorboards (~£10/m2), ?glued along joins and joists and screwed to joists?
• 21mm hardwood plywood ripped to planks (~£12/m2), glued and screwed to joists perhaps glued along joins. I've seen some nice results online that people have got with this.

 

Particularly above the garage, a key advantage of the last two options is that they could be left bare as the finished floor. It may create an acoustic issue as carpets really help against that, but it could look good and be functional. A concern with Redwood floorboards is that they could be a bit soft and end up very dented. Is there a treatment that can be used to harden the top surface a bit.

 

Trusses are on 600mm centres.

[MikeGrahamT21]

Don't forget OSB3 TG4 which at 18mm will also work with the 600 ctrs, or 22mm if you want something firmer (22 OSB3 will be firmer than 22 chipboard)

[MortarThePoint]

1 hour ago, MikeGrahamT21 said:

Don't forget OSB3 TG4 which at 18mm will also work with the 600 ctrs, or 22mm if you want something firmer (22 OSB3 will be firmer than 22 chipboard)

 

An advantage of the chipboard over larger sheets is that it is 2400 x 600 so I can lay it on my own.

[Dudda]

1 minute ago, MortarThePoint said:

An advantage of the chipboard over larger sheets is that it is 2400 x 600 so I can lay it on my own.

The OSB3 that's T&G is the same size at 2400x600mm. This is what I'd use. 

[MikeGrahamT21]

Yeah, and B&Q do an even shorter version that fits in the back of most cars, but only 18mm...

 

https://www.diy.com/departments/smooth-osb-3-floorboard-l-1-69m-w-634mm-t-18mm/1696227_BQ.prd

 

Not the cheapest agreed, however i find its got a much superior surface to normal OSB3 TG4's, highly sanded, you can actually skate over it in socks! LOL

[TonyT]

if I were thinking what could I get in the car and what was way to lay I would go for floorboards in this situation, easier to handle, manoeuvre, cut and fix down.

 

[MortarThePoint]

In important consideration in all of this is Part E of building regulations:

18mm OSB3 and CaberFloor are below that 15kg/m2 requirement. I think 22mm OSB3 is also below 15kg/m2, but it is hard to find information on that. I spoke to a technical person at Norbord and they said it may have an issue there. [NOTE: normal 12.5mm wallboard plasterboard doesn't meet the 10kg/m2 requirement either].

 

Link to document

[Moonshine]

8 minutes ago, MortarThePoint said:

In important consideration in all of this is Part E of building regulations:

18mm OSB3 and CaberFloor are below that 15kg/m2 requirement. I think 22mm OSB3 is also below 15kg/m2, but it is hard to find information on that. I spoke to a technical person at Norbord and they said it may have an issue there. [NOTE: normal 12.5mm wallboard plasterboard doesn't meet the 10kg/m2 requirement either].

 

This construction is really a 'deemed to satisfy' construction, and what it satisfies is the requirement of ADE that the internal walls and floor meet min Rw 40 dB. 

 

You can meet Rw 40 dB with out the insulation and 18mm board, though with 15mm wall board ceiling.

 

https://www.gyproc.ie/sites/default/files/C106029.pdf

[MortarThePoint]

5 minutes ago, Moonshine said:

 

This construction is really a 'deemed to satisfy' construction, and what it satisfies is the requirement of ADE that the internal walls and floor meet min Rw 40 dB. 

 

You can meet Rw 40 dB with out the insulation and 18mm board, though with 15mm wall board ceiling.

 

https://www.gyproc.ie/sites/default/files/C106029.pdf

 

So if I understand it that document is setting out a valid substitute to the Part E "Internal floor type C".

[PeterW]

1 minute ago, MortarThePoint said:

important consideration in all of this is Part E of building regulations:

Why are you looking at Part E for floors as it’s not required for a single dwelling 

[ADLIan]

Part E applies to intermediate floors and certain partition walls within a dwelling. More onerous standards apply to party walls and separating floors between dwellings

[keith65]

If I was putting down Redwood flooring I would not glue it as it will move if you glue it it will split just nail it with 65mm lost head nails

[MortarThePoint]

37 minutes ago, PeterW said:

Why are you looking at Part E for floors as it’s not required for a single dwelling 

 

As I read it Part E does apply within a single dwelling. Table 0.1a and 0.1b set out values for 'separating' walls and floors which I presume means between dwelling units (e.g. flats) and the prevailing value for floors is around 45 dB for airborne sound. Table 0.1c sets out values within a dwelling and has a value of 40dB.

[Moonshine]

58 minutes ago, MortarThePoint said:

So if I understand it that document is setting out a valid substitute to the Part E "Internal floor type C".

 

No its not, those detailed in ADE are just examples of how you can meet the requirement of ADE for R_w 40 dB for internal partitions. You could have a partition floor made solely of cheese and as long as you had a lab test showing it met R_w 40 dB it would meet the requirements.

 

Though meeting the fire regs for a cheese floor would be interesting, and a tasty fondue.

 

 

[Moonshine]

42 minutes ago, ADLIan said:

Part E applies to intermediate floors and certain partition walls within a dwelling. More onerous standards apply to party walls and separating floors between dwellings

 

Just to build on this, the requirements for ADE for internal partitions (R_w 40 dB) is determined by a lab based measurement, you don't do testing on site for internal partitions.

 

For separating walls and floor between dwellings (attached houses / flats) you have to do on site testing (unless using the Robust Details scheme), to demonstrate compliance of meeting the minimum requirements of ADE (new build D_n,Tw + C_tr >= 45 dB, L_n,Tw <=62 dB), testing requirement frequency is usually 10% of constructions on site. 

[PeterW]

17 minutes ago, MortarThePoint said:

 

As I read it Part E does apply within a single dwelling. Table 0.1a and 0.1b set out values for 'separating' walls and floors which I presume means between dwelling units (e.g. flats) and the prevailing value for floors is around 45 dB for airborne sound. Table 0.1c sets out values within a dwelling and has a value of 40dB.

Only certain rooms (bathrooms for example) and habitable rooms. Egger Protect is 16.2kg/sqm for 22mm from memory. 
 

 

[MortarThePoint]

12 minutes ago, PeterW said:

Egger Protect is 16.2kg/sqm for 22mm from memory. 

 

I've found it very hard to find density information. This link suggests Egger Protect has a density of 620kg/m3 which would give an area density of 13.6kg/m2 for 22mm thickness.

[SimonD]

If it helps, we had redwood floorboards in our old house simply varnished with Ecos Paints (I think it's now called Lakeland paints) interior/exterior clear varnish. Over 12 years it all held up better than our engineered oak floor. I'd be surprised if you could buy it for only ~£10/m2. I just got a price for 40m2 of softwood t&g interior wall cladding which came in at about £25/m2 and that's obviously smaller dimension than floorboards. However, you wouldn't need an additional floor cover.

[PeterW]

On 07/05/2021 at 11:12, MortarThePoint said:

 

I've found it very hard to find density information. This link suggests Egger Protect has a density of 620kg/m3 which would give an area density of 13.6kg/m2 for 22mm thickness.

So I’ve never had a BCO pull up on the board density and it’s the widest used board in new builds now so unless you’ve got the worlds worst BCO, I would put 22mm Egger Protect down and move on ..?? 

[SimonD]

1 hour ago, PeterW said:

So I’ve never had a BCO pull up on the board density and it’s the widest used board in new builds now so unless you’ve got the worlds worst BCO, I would put 22mm Egger Protect down and move on ..?? 

 

To put the board density question into perspective, I've just bought a load of Knauf Aquapanel Outdoor - the given density for this board is 16kg/m2. Is there actually a timber based board that doesn't contain cement that gets up to 15kg/m2 without a silly thickness?

[MortarThePoint]

22mm CaberFloor states it is 15kg/m2. 18mm OSB3 will be well under. As @PeterW states it's unlikely any BCO will care though.

[SimonD]

16 hours ago, MortarThePoint said:

18mm OSB3 will be well under. As @PeterW states it's unlikely any BCO will care though.

 

I completely agree. I have 18mm OSB and density has never been a consideration by anyone. It's only the structural performance of the board that's ever been considered. It's worth keeping in mind that, as @Moonshine suggested, the building regulations aren't entirely prescriptive and you've got detailing options, often provided by materials manufacturers.

[Mr Punter]

I have not been able to find 2400 x 600 TG4 ply or OSB thicker than 18mm.  I was hoping to get it at 22mm.

[PeterW]

16 minutes ago, Mr Punter said:

I have not been able to find 2400 x 600 TG4 ply or OSB thicker than 18mm.  I was hoping to get it at 22mm.

wisa are the only ones that make spruceply in 22mm T&G from memory. 
 

https://www.buildersmerchant.com/product/plywood-flooring-boards-tongue-groove-22mm/

[SimonD]

2 hours ago, Mr Punter said:

I have not been able to find 2400 x 600 TG4 ply or OSB thicker than 18mm.  I was hoping to get it at 22mm.

 

Why are you looking for 22mm? The 18mm osb is at least 'equivalent' to a 22mm P5 and good for 600mm c/c. I think the only times 22mm is used is in commercial projects and I suspect special order only.