Preparing my walls for en-suite

[Richard C]

The are many ways of doing it but I usually use one of these;
http://www.amazon.co.uk/gp/product/images/B00032II4A/ref=dp_image_0?ie=UTF8&n=79903031&s=diy
& lay it flat on the floor to cut through (across) the boards at the point where I want to remove them; i.e. against the wall or down the centre of a joist. It works surprisingly well & with a bit of practice you can cut through individual boards with minimal damage to its neighbors. Check first that there are no cables or pipes under the boards. With tongue & groove boards, take a 4” bolster chisel & hammer it down between the adjacent boards to break through the tongue either side of the first board; pick the easiest board you can get at in the centre of the floor. Lever the board up from one end to the other using a couple of pry bars; once you have the first one up the rest are relatively easy, again using the pry bars.

Depending on weather you’re lucky or not you may find enough of a joist below the wall in which case the new ply will just sit on the joist. If there is a joist within, say 4 inches of the wall, you probably wont need anything as the ply will provide sufficient support on its own & you’ve never going to get any load to speak of that close to the wall. You may need to install a sister joist (a length of wood bolted/screwed onto the existing joist) or even a series of noggins (pieces of wood fixed between the joists) to provide additional support. On the adjacent walls where the floorboards run parallel with the wall, it’s usual to fix noggins but, again, if the edge of the new ply floor is going to be in such a location where it’s unlikely ever to be subjected to any significant loading, you don’t really need anything; it’s a question of assessing individual circumstances.

Fit the new ply floor in the largest sections that practicalities will allow with joins running down the centre of a joist; any joins in the main floor area across the joists must be fully supported with noggins. Seal the back of the ply with an SBR sealant & screw it down onto the joists using suitable length screws, 150mm apart. It sounds like a lot of work but in reality with a clear room it should only take a day or so to get the new floor in place depending on how many noggins you have to put in.

Always use quality trade adhesive & grout suitable for the application, never use cheap DIY products.

 

[chriselevate]

Just a couple of questions on top of the last post.

When new builds are built don't they use board for the floors in these cases? The reason I ask is we've got a few friends who live in new builds and the floorboards are like paper. You can hear every movement from the floor above and they creak and awful lot. Our old fashioned floorboards seem much more solid and better quality than the rubbish they use today?

Is this the case if I remove the above mentioned floor boards?

 

[Richard C]

New builds invariably use crap T&G chipboard or “crapboard” as I call it. Some builders will use moisture resistant in bathrooms but others simply don’t bother; that & the fact they use ordinary PB wall boards to dry line, don’t tank it & use the cheapest products they can get hold of is why the bathrooms in so many new builds need refurbishing after just 3 years or so years in some cases. A few of the better individual & more conscientious builders may fit WBP in the bathroom or en-suite if the floor is going to be tiled but not that many I would guess.

I have a 60's property with tongue & groove floorboards & they are still as good as the day they were put in; I still took them up & replaced with WBP in the bathroom & en-suite though.

 

[chriselevate]

Hi Richard,

Thanks for your help.

The scorpian saw is able to get up to a wall then? And the depth of it will be managable? Obviously I don't want to be hacking the joists underneath to bits?!

Thanks for your advice on the new builds. I didn't want to start throwing away loads of floorboards only to find that the replacement wasn't as good as the originals.

Do I need to keep the edge of the new boards away from touching the enterior wall? I mean I'm going to use the membrane and dot and dab the the walls so I wondered what order you would do these two things in?

You talk about sealing the back of the ply with an RBS sealant? What do you mean by this?

As the room isn't very big at all it shouldn't take long to do.

Cheers

 

[Richard C]

The scorpian saw is able to get up to a wall then? And the depth of it will be managable? Obviously I don't want to be hacking the joists underneath to bits?!

Honestly, it’s far more versatile & accurate than it looks & you should quickly the hang of how to use it to best advantage, especially if you’re used to hand tools. You can get specialist saws but it’s my saw of choice when taking up floorboards as it’s possible to cut right though individual boards with barely a mark the joist underneath once you’re used to it; practice on an old f/board if you’re not sure.

Thanks for your advice on the new builds. I didn't want to start throwing away loads of floorboards only to find that the replacement wasn't as good as the originals.

Floorboards are infinitely better than crapboard but WBP is equally better than f/boards for tiling onto.

Do I need to keep the edge of the new boards away from touching the enterior wall? I mean I'm going to use the membrane and dot and dab the the walls so I wondered what order you would do these two things in?

Normally it wouldn’t be a problem but given the damp history, it would wise. If you fix the wall membrane first down to joist level that will be enough. If not, I would put a lump of damp membrane (or thick plastic) down around the outside wall edge over the joist(s), fix the ply & then cut off the excess flush; or you could buy a roll of DPC & use that.

You talk about sealing the back of the ply with an RBS sealant? What do you mean by this?

RBS sealer;
http://www.bal-adhesives.co.uk/products/bond-sbr
but there are many other SBR sealers around; this ones not cheap but you won’t go far wrong with the rest of their products either. It’s a waterproof sealer as opposed to PVA (often mistakenly used) which is basically wood glue & is water soluble. The idea is to stop any moisture being absorbed into the back of the ply (as opposed to the front which is covered in tiles & waterproof adhesive), expanding & curling the front floor side of the ply upwards cracking the tile adhesive & grout. That’s the theory but in reality (& at the risk of possible criticism), I’ve got to admit I don’t always do it; but given your previous damp problems I think it would be very wise.

 

[chriselevate]

So in an ideal situation I'd be using MR board on all the walls, this need priming before plastering? And I can leave the shower enlosure un-plastered and tile directly onto this surface after priming it? And I'd use 18mm or 25mm WBP to replace the existing floorboards with and then use RBS sealer on the backs of these boards. Once this is done I can use the BAL products to tile directly onto the board?

Alternatively I can use normal 12.5mm PB, plaster them all but the shower area which I can paint tanking onto and then tile directly onto?

Just checking the thing through before I get prices and make a decision.

By the way the shower trap is located in the centre of the shortest edge of the shower tray (i.e. it could go at the back of the shower at against the rear wall or at the front in the middle of the door), Where it be best to locate this trap?

Thanks guys.

 

[dextrous]

Nearly there - the MR board in the shower area still requires tanking.

The shower trap should be placed in a position which enabled you access to join the waste pipe onto, plus also ideally not having to cut a large notch out of a joist! If you go for replacing the floorboards with ply as Richard suggests, it will be self evident where the best place to locate it will be.

 

[chriselevate]

Sounds good!

I mean the wall which is pictured as 'E' and 'D' in the diagram is all regular plasterboard at the moment.

Would it make a big difference if the new plasterboards I was adding (about 6) were normal ones or MR board? How much do the MR ones cost? Is it much more than the normal boards?

What is the material of the MR boards like? is it the same as normal PB? Is it the cut the same way or different etc?

I shouldn't have to remove the existing PB that's on 'E' and 'D' or overboard should I?

Cheers

 

[Richard C]

I shouldn't have to remove the existing PB that's on 'E' and 'D' or overboard should I?

I’ve sort of lost track of what you have & where; if D & E is currently ordinary 10mm wallboard, is it a stud wall or have you dot & dabed? I would not overboard existing boards if you’ve already put them up but would much rather see a waterproof tile backer board in the shower area & 12.5 boards rather than 10mm which are primarily for use on ceilings. MR board & tank it would be the next best option but the cost of a decent tile backer board is about the same as using PB & a tanking kit.

What’s on B & C, have you actually over boarded the membrane yet?

Would it make a big difference if the new plasterboards I was adding (about 6) were normal ones or MR board? How much do the MR ones cost? Is it much more than the normal boards?

I would only ever use MR in bathrooms; they are more expensive but the overall cost for 6 boards is going to be £20-£30 which is insignificant given the overall cost of the project. Use square edge boards not taper edge.

What is the material of the MR boards like? is it the same as normal PB? Is it the cut the same way or different etc?

MR is impregnated with a moisture resistant additive in both the core & paper linings which are green rather than the grey of ordinary wall board. It cuts exactly the same; score through the paper face with a sharp Stanley knife, snap it back & cut through the back lining paper. Cement backer board can also be cut with a Stanley knife.

That’s SBR sealer not RBS; - RBS = Royal Bank of Scotland!

If you know what tiles you’re using on the floor & walls, I will advise which adhesive/grout you need.

 

[chriselevate]

Hi Richard,

Thanks for your message. Here's a copy of the photo I included originally:



D&E is in the enclosure and measures 1670 by 2650 high and it's a stud wall that contains the shower mains pipe, electricity supply to the shower and towel rail too. Is it the best option to rip this off and use the MR plasterboard and tank it along with the C & B walls?

No I haven't done anything yet. B & C are both masonary walls that I'll be using the membrane on and then overboarding wth the MR plasterboard.

Just spoke to Build Centre and they only have tapered MR PB's and they are £7 each + vat for the 2.4 x 1.2 boards. Good price? This was for cash... is it better if I could buy them using an account?

They also said they have 3 grades of WBP 18mm Ply..... Soft Wood, Beeched & Hardwood Spruce. I'm suggesting 18mm as the boards I'm pulling up are 18mm floorboards. Would you suggest going any thicker?

Measurements for the room are:

Wall A 3270
Wall H 1200
Wall G 1600
Wall C 750

By the way which of the boards is the MR Board:

* Fireshield
* Vapourshield
* Moistureshield
* Soundshield
* Thermal Laminate (Plus)
* Aquapanel

(take from build centre website)

Thanks

 

[Richard C]

D&E is in the enclosure and measures 1670 by 2650 high and it's a stud wall that contains the shower mains pipe, electricity supply to the shower and towel rail too. Is it the best option to rip this off and use the MR plasterboard and tank it along with the C & B walls?

On a stud wall I would normally say use Aquapanel no question but given what I’ve said below about using MR boards over your membrane & tanking that wall, you will need to buy a tanking kit anyway so you might as well stick with PB. Being stud, it will be relatively easy to remove so I would prefer to see it replaced with 12.5mm MR boards. 9.5mm PB is really only meant for ceilings, it’s rather marginal for use on walls & may warp if you’re going to hang anything heavy on it & may not provide enough support for large heavy tiles.

No I haven't done anything yet. B & C are both masonary walls that I'll be using the membrane on and then overboarding wth the MR plasterboard.

Your case is a little unusual for me as it’s not a situation I’ve personally been in before. Under normal circumstances, there is no question I would say use Aquapanel; the problem is that it cant be dot & dabbed or at least not without adding additional mechanical fixings & you don’t want to be putting screws though your nice new damp membrane! On balance & in your situation, I would use 12.5mm MR plasterboard dot & dabbed over the membrane, tank it & tile over that.

Just spoke to Build Centre and they only have tapered MR PB's and they are £7 each + vat for the 2.4 x 1.2 boards. Good price? This was for cash... is it better if I could buy them using an account?

I must admit I don’t use Build Center but any account ties you down too much in your situation so I wouldn’t bother, you won’t save much if anything. £7 sounds about right but go in your work clothes if possible & don’t be frightened to ask for a discount; you may be able to source them cheaper but probably not much & the overall cost difference for just a few boards isn’t worth the hassle. You need square edge boards though so if BC doesn’t have them, look elsewhere.

They also said they have 3 grades of WBP 18mm Ply..... Soft Wood, Beeched & Hardwood Spruce. I'm suggesting 18mm as the boards I'm pulling up are 18mm floorboards. Would you suggest going any thicker?

In most cases 18mm will be sufficient but it depends on the direction, size, spacing & span of the floor joists as this, in turn, affects the overall rigidity of the floor. It’s something that’s impossible for me to judge over a forum but in which direction do your joists run? If the floor is likely to flex unduly or you’re in any doubt, go to 25mm.

Soft wood WBP is all you need & an exterior grade will do fine, you don’t want anything fancy as it’ll never be seen; get full size boards, 2.4 x 1.2. Did they not ask you what it was for? Sometime these guys seem to take great delight in being “picky” if you’re not entirely sure what you need which I find annoying.

By the way which of the boards is the MR Board:
* Fireshield
* Vapourshield
* Moistureshield
* Soundshield
* Thermal Laminate (Plus)
* Aquapanel

The products quoted are “Knauf” which I have used on occasion; the ones I refer to are “British Gypsum” which I mainly use purely because they are easier for me to get. They are effectively the same though & Moistureshield = Moisture Resistant. Knauf also do both square & taper edge, it’s the square edge boards you want or you’ll have to mess about filling the tapers before you can tile; if Build Center don’t have SE boards, go elsewhere.

 

[chriselevate]

Right.... time for an update and some advice if anyone can help?!

I've taken the bull by the horns and removed the 2 - 3 sheets of plasterboard on the wall that was stud partitioned. It was nailed to the wall every 3 inches so it took me about 3hrs to get rid of it! And it was SOOOOO messy!

I've also ripped up half of the floor boards so far.... my question is.....

The threshold seems to run exactly half way between two joists! Typical!
What would you do to sort this before laying the new stuff? The rest of the wall as show in the diagram isn't so bad as it runs a lot nearer the joist... about 4 inches between where the edge of the flooring is and the next joist is.

Here's the visuals.... The photo has wall 'H' in front of me btw.

 

[dextrous]

If it were me I'd get a couple of cross members between the joists and screw additional timbers between them to support the forthcoming joint at the threshold and the board at the edge of the room where it meets the wall (together with being an additional support for the actual stud wall)- like a few elongated H frames, if you get my meaning. This will most likely require you removing another board just beyond the one on which the current wall stands.

 

[chriselevate]

Thanks.

What sort of wood would you use for cross members? Looking at the photo is it essential that I support this thresshold section? I guess that the constant walking into the bathroom will make this part a weak spot and the last thing I want is for there to be any movement on the new ply and the tiles fixed to it.

Also.... the other part of the wall I was talking about that you can't see on there photo has the stud wall and floor boards finish about 4 inches from the joist..... this is surely going to be impossible to add in cross members here or additional support? Would it be ok to leave it in this part?

 

[dextrous]

What sort of wood would you use for cross members? Looking at the photo is it essential that I support this thresshold section? I guess that the constant walking into the bathroom will make this part a weak spot and the last thing I want is for there to be any movement on the new ply and the tiles fixed to it.

3" or 4" by 2"

Also.... the other part of the wall I was talking about that you can't see on there photo has the stud wall and floor boards finish about 4 inches from the joist..... this is surely going to be impossible to add in cross members here or additional support? Would it be ok to leave it in this part?

I think the problem here will be having an unsupported edge to your ply floor, which again would be resolved by the method previosly described, and will be accessible by lifting the board(s) outside the room. The cross members between the joists will provide the extra support, since they will be tight up against the existing floor from beneath anyway (screwing them into a holding place through the existing floorboard outside the bathroom will guarantee this whilst simultaneously keeping you hands free to screw the ends of these timbers into the joists on both sides of the wall)