Final Q's before i rip up my floor

[markyyyyyy]

I have sloping floors (approx 1.5 - 2 inch slope over a 3 metre span) which i believe is due to historical subsidence. The house was built in 1902.

Here is a pic of my floorplan with the sloping area of concern. It was a 2 up 2 down however they have now had stud walls put in to create a smaller bedroom and a bathroom, as per floor plan.

The slope stairs at the top of the stairs, and slopes in the direction of 'bedroom 2', and also the bathroom. So effectively, as it used to be, the whole of the back of the house slopes.

I intend on taking out the floorboards and exposing joists, sistering the joists level, and reinstating the floor.

The joists run from front to back of the upstairs house, and the floorboards from L - R

My main questions are:

1. If i have to raise the floor and the point at which it raises means that the finished floor will be messing about with the door frames, do you shave the door frame in situ or take them off?
2. Would you re-lay the floor (typial floor boards) or would you install somthing such as moisture resistant loftboard instead?
3. Any issues that may present themselves to me that i may have not noticed?
4. Seems a stupid question, but are the stud walls okay to be left in or do i have to take them out to have an open area of joists?
5. Probably my most important question - Do i start levelling at the top of the stairs / landing area and work from there - the slope moves away from the stairs so it will be the high point.

Thanks

 

[markyyyyyy]

Anyone any ideas?

 

[martin hill]

Mark the P5 chipboard will depend on your joist spacings. Check if you need 18mm or 22mm. You can cut the bottom of the door frame with a multi tool to slide the boards under. The issue you have is where the stud wall for the bathroom/Bedroom 2 is fixed on the existing floor. It may not be over a joist so you would have to leave the old floor either side if not ripping it out.

 

[martin hill]

Talking of level floor. I must of passed these 2 houses a million times. Each time i do i always want to knock on and see if they live on the left hand slant or have all the floors been corrected inside.

https://www.google.com/maps/@53.489...4!1s1UDXK9iXssKtN_O79HQdHg!2e0!7i16384!8i8192

 

[dazlight]

What floor covering are you planing in the rooms.

 

[markyyyyyy]

Mark the P5 chipboard will depend on your joist spacings. Check if you need 18mm or 22mm. You can cut the bottom of the door frame with a multi tool to slide the boards under. The issue you have is where the stud wall for the bathroom/Bedroom 2 is fixed on the existing floor. It may not be over a joist so you would have to leave the old floor either side if not ripping it out.

Hi Martin

Many thanks for your reply.

What joist spacing dictates 18mm or 22mm I assume wider spacing will accommodate a thicker floor?

I do actually plan on ripping out th floor in the bathroom as that's just as bad. Does this mean the stud wall has to come out? Or could I just install another joist so that it goes along the edge of the room to avoid ripping wall?

Cheers

 

[markyyyyyy]

What floor covering are you planing in the rooms.

Carpet in bedroom 2 and tiles or laminate in bathroom

 

[dazlight]

And what on the landing ?

 

[Diver Fred]

What is the partition walls Studding and Plasterboard or Studding with Lath & Plaster. Eitherway think the walls have to come down.

As for leveling the new floor I'd start at the high spot and level up to that.

When you sister the joists do treat with woodworm treatment as you go - it is now possible to Aqueous based treatment so there is no odour to linger. Both Old and new timbers. Take 'photos of the work and keep the receipts for when you sell on (or 30 years which ever comes first).

 

[markyyyyyy]

And what on the landing ?

carpet on the landing

 

[markyyyyyy]

What is the partition walls Studding and Plasterboard or Studding with Lath & Plaster. Eitherway think the walls have to come down.

As for leveling the new floor I'd start at the high spot and level up to that.

When you sister the joists do treat with woodworm treatment as you go - it is now possible to Aqueous based treatment so there is no odour to linger. Both Old and new timbers. Take 'photos of the work and keep the receipts for when you sell on (or 30 years which ever comes first).

thanks for your reply.

Okay so from what a few have said it sounds like the walls best to come down. Would i be able to reuse stud work or should i go brand new?

I was planning on using 4x2 treated timber for the sistering of joists, would this be sufficient? with M10 bolts through at every 1m or so?

High spot is definitely the landing at too of stairs, so i'll start from there.

I have a feeling this will cost a lot!

Edit: What woodworm treatment do you reccommend? Do i use it on the new and old joists or just old?

 

[Deleted member 174758]

What joist spacing dictates 18mm or 22mm I assume wider spacing will accommodate a thicker floor?

As no one seems to have answered this..... 22mm will always result in a stiffer floor than 18mm and for that reason is preferable. Maximum joist spacing for 18mm is 400mm/16in whilst 22mm can span 600mm/24in should it be necessary. When installing chipboard flooring it is recommended by most manufacturers that you glue to the joists as well as gluing the tongues of the boards before screwing in place.

Does this mean the stud wall has to come out? Or could I just install another joist so that it goes along the edge of the room to avoid ripping wall?

TBH you'll probably find that at least some of your walls are atop either a thicker/sistered ,joist (i.e a trimmer) or possibly a masonry wall. Those can stay in. Where the walls are more modern with modern timbers and plasterboard it's up to you, but if it isn't too difficult I'd try to work round this rather than ripping out. The biggest issues in ripping out stud walls in any house with lath and plaster walling is that apart from being hard work, the volume of waste generated, the fine dust from lime plaster (which gets everywhere in the house and means the people doing the job will need goggles and dust masks - try getting them at the minute), the soot that invariably is also dislodged from all sorts of nooks an crannies, is the fact that when you've stripped it out the timber framework may not be suitable for reuse even assuming that you can get it apart without damaging it in the first place and that the ceiling hasn't fallen or cracked because the wall you taken out was supporting it. Even if it doesn't drop, expect to have to repair cracks in the ceiling near to where any demolished wall stood

BTW on domestics M10 coach bolts should be fine. Remember to add star (bulldog) washers between the joists and the sistering timbers. We generally install bolts at centres mo greater than 600mm these days. Buy treated timbers for the sistering if possible. Any original joists showing signs of rot st the wall pockets will need to be doubled up with an identical size (treated) joist which is pocketed into the wall at each end. Ends need to be envelope wrapped with felt and require 100mm bearing at each end inside the wall

 

[markyyyyyy]

As no one seems to have answered this..... 22mm will always result in a stiffer floor than 18mm and for that reason is preferable. Maximum joist spacing for 18mm is 400mm/16in whilst 22mm can span 600mm/24in should it be necessary. When installing chipboard flooring it is recommended by most manufacturers that you glue to the joists as well as gluing the tongues of the boards before screwing in place.


TBH you'll probably find that at least some of your walls are atop either a thicker/sistered ,joist (i.e a trimmer) or possibly a masonry wall. Those can stay in. Where the walls are more modern with modern timbers and plasterboard it's up to you, but if it isn't too difficult I'd try to work round this rather than ripping out. The biggest issues in ripping out stud walls in any house with lath and plaster walling is that apart from being hard work, the volume of waste generated, the fine dust from lime plaster (which gets everywhere in the house and means the people doing the job will need goggles and dust masks - try getting them at the minute), the soot that invariably is also dislodged from all sorts of nooks an crannies, is the fact that when you've stripped it out the timber framework may not be suitable for reuse even assuming that you can get it apart without damaging it in the first place and that the ceiling hasn't fallen or cracked because the wall you taken out was supporting it. Even if it doesn't drop, expect to have to repair cracks in the ceiling near to where any demolished wall stood

BTW on domestics M10 coach bolts should be fine. Remember to add star (bulldog) washers between the joists and the sistering timbers. We generally install bolts at centres mo greater than 600mm these days. Buy treated timbers for the sistering if possible. Any original joists showing signs of rot st the wall pockets will need to be doubled up with an identical size (treated) joist which is pocketed into the wall at each end. Ends need to be envelope wrapped with felt and require 100mm bearing at each end inside the wall

Many thanks for your help
So the bulldog washers go BETWEEN the new joist and old joist? Do they grip or something? Any particular size washer needed?

By wall pockets, are you referring to where the timber joist sits into the section of wall that is cut out?

Is damp proof membrane okay instead of felt? I've got some lying around?

I would much rather keep the walls in situ - one of my concerns was actually all of the mess and also there is artex on the walls which will have asbestos in so i daren't destroy them.

So can you confirm that loftboard is suitable to use as the sub floor or is something else preferable?

 

[Deleted member 174758]

Bulldog washers go in between the old joist and the sistering timber, yes. Toolststion call them timber connectors and sell them for M12 bolts (a standard size: part no. 30004)

A wall pocket in this case means a section of brickwork broken out to allow the end of the joist to sit inside it. One brick width (4in/100mm) is what you aim for. Once sistered the pockets are refilled as needs be using mortar and brick (reuse the stuff you, hopefully, carefully chopped out)

Felt is preferable, but DPM will work. The idea is to wrap it in one piece, a bit like a parcel. You start on the underside so that water cannot be trapped in the envelope

I wouldnt use loftboard, especially as you have a bathroom. Better to go for something like Egger P5 or Caberdecor P5 t&g chipboard. Use D4 PVA (again, see Toolstation) and glue down to the joists as well as ensuring there is enough glue on the tongues (you actually need to squeeze the glue into the grooves). Use decent quality screws (4.5 or 5.0 x 50) fixed on 150mm centres every joist. Add battening to the sides of joists if needed to provide support for the joints (all end joints MUST be fully supported) or alternatively fix noggins between adjacent joists to support short ends (3 or 4 for every 600mm wide board) Stagger the joints between rows of board. They should look like brick pattern

 

[martin hill]

Hi Mark.

Well been busy in the garden. J & K beat me to answering with some sound advice as for the stud wall i'd leave it in. Make sure the screws you use are full thread so they grip the p5.

As you lay the P5 boards down us a perm black marker and draw on them the layout of any pipework and cables underneath. Be a god send in the future if you need anything doing.