Remedial Structural Work.

[daiking]

I had a thread on ebuild about a dodgy first floor room where the joists had not been properly supported when the wall brow was taken out. Well its probably (a lot) worse than that. http://www.ebuild.co.uk/topic/18951-existing-floor-joists-not-tied-into-new-structural-beams/

 

As part of the rear and side extension the rear corner ground floor wall was taken out and steelwork inserted to support the first floor and roof. I had discovered that the floor joists were not properly supported on the beam and there were some cracks in the plaster but I hadn't realised how far it had moved.

 

The cracks are concentrated around the wall openings. Here the old corner of the house where the steels meet is to the left of the window: 

 

 

 

Ive tried to mark adjacent to the cracks with a blue marker to highlight them, it ran out. There is one  to the right of the window that goes up and along the ceiling. Some below the sill too:

 

 

This room is still the original float sandy plaster with a recent skim on top and the original plaster was not great anyway so cracking is not a massive surprise. Opposite the wall with the window is the wall with the door. 

 

 

 

I'd noticed the cracks from the top right corner but hadn't thought about this wall fully till recently. 

 

This is an internal first floor block/brick or whatever but there is no wall supporting in downstairs. It is literally sat on the floorboards directly on a joist. I was unsure quite how this joist was supported given my concerns about the floor joists. Looking at the corner of the door that's cracked, it looks like the whole thing dropped 15mm across the width of the door let alone the 2.2m width of the room. 

 

[daiking]

This is the other side of the wall, it's the top of the stair with a quarter turn to the right onto the original landing and a quarter turn to the left in the first floor extension. This wall was skimmed after but even so  it's got the same crack from the door frame corner and looks like it's dropped.

 

The stairs quarter turn

 

 

I took some plaster off to better reveal the structure. There's a joist, unmolested where it sits in the wall to the right but presumably now not seated on the left. On top of that is the end of the bedroom floorboards, then a 4x2 sole plate and the wall built on that.

 

 

 

Going back into the bedroom this is the best I can see for the moment of this joist end. God knows what's actually supporting it at the moment but it's 10 months and counting. probably supported by the floorboards on the adjacent joist.

 

sole plate on floor boards

 

 

joist end

 

 

I didn't think this wall could drop but now I understand the construction a little better and seeing the orientation of that brick in the second last photo, I don't think this wall is tied into the original inner brickwork leaf as it was constructed after. 

 

Edited October 10, 2016 by daiking

[daiking]

So if that wasn't bad enough, I'd knocked off a bit of plaster so I may as well have carried on. So far, this is the base of the inner leaf supported on the steels. Massive gaps and loose bricks. 

 

 

 

 

 

Which leaves me wondering what the fudge to do next?

 

[PeterW]

Any way you can take down that wall and replace it with a stud wall..? It would seriously lighten the load and also allow a proper look at what is tied to where...

[daiking]

18 minutes ago, PeterW said:

Any way you can take down that wall and replace it with a stud wall..? It would seriously lighten the load and also allow a proper look at what is tied to where...

 

 that had crossed my mind as I do have a sort of plan of what needs doing but wanted to be guided. I didn't want to suggest that first as I hoped for something better.

 

i can imagine propping it up from below but jacking it from my nice tiled floor? Ouch.

Edited October 10, 2016 by daiking

[daiking]

The other thing is that the wall is supporting the ceiling joists but i suppose they could be propped from the landing and stairs

 

i certainly wouldn't do it

from the bedroom floor in current state.

Edited October 10, 2016 by daiking

[daiking]

Managed to upload these. In black for onoff's benefit.

[Declan52]

Block work upstairs sitting on a sole plate is pretty common, had it on my old house. Same goes with walls not tied in properly, they more than likely have used 4 inch nails to tie them in.

Put carpet on the tiles and lay a plank on it. Put the accrows on the plank with another plank across the joists to support it so it won't sink any more. 

How is the steel work supported at the bottom as in its there any chance it could have settled and sunk a few mm causing the joists the move and crack.

If the steel's are ok the you can use the accrows to lift the joists up and pack the few inches between it and the steel.

 

[daiking]

The ends of the steelwork (in the existing walls) sit on pad stones. 

 

The steel beams were installed long before the wall was taken out and for a long time were installed in the walls. The fill in block work that was visible on the old external leaf was very tidy. I would have thought it was all really stable before the wall came out. Obviously not. I'll have to

search for some photos. I can't remember if the pad stones were Installed initially or at the time of the knock through. 

 

The difficulty with supporting from below is probably best explained with another picture. That stair quarter turn projects down

through the ceiling below. It was originally part of house kitchen. With the extension a enclosed this

within a cupboard so it's tricky to get at the end of the joist.

 

i know the construction method is typical, the wall dividing the front and back bedrooms is similar, brick on floor boards and does not line up with the ground floor dividing wall. However before the ground floor wall was removed, I'm pretty sure it all lined up ok.

Edited October 10, 2016 by daiking

[Declan52]

Could the pad stone have sunk under the weight if the brickwork is not great.

Measure the four corners floor to ceiling and see what the difference is. Ceiling should be the same the whole way along so your just checking both bad corners against the other two good ones.

[daiking]

I'll try measuring the ceilings heights to compare. 

 

The padstones are plastered in on the ground floor and as yet show no obvious movement in the plastering. The care seems to have been taken with the external leaf not the internal. Although I understood the inner leaf was more important. For instance would you leave those gaps you can see it the last few photos?

[ProDave]

I am confused.  I thought this problem was the result of building work done and a supporting wall being replaced by a beam. But your drawings seem to show it has always only been supported by a floor joist?

 

My previous 1930's house was like this. The downstairs wall was about 1/3 the span from front to back. But upstairs a brick wall that separated two bedrooms meant a lot of weigh supported mid span by the floor joists.

 

When I bought the house there had clearly been a lot of movement, the bend in the floor was clear to see and a door frame was very out of square.  The surveyor noted it was at the limit of acceptable deflection and if further movement was noted a steel beam should be inserted under the wall to support it.

 

In the 13 years I was there it did not move any further. As part of the work I did on the house, I re fitted the door frame and made it square. The plaster did not crack again and when i sold it, there was no mention of it at all on the buyers survey.
 

[Declan52]

The inner leaf is more important as it carries the roof. Shouldn't be any gaps in any wall. If it can come down i think you will have to bite the bullet and replace with stud.

[daiking]

5 minutes ago, ProDave said:

I am confused.  I thought this problem was the result of building work done and a supporting wall being replaced by a beam. But your drawings seem to show it has always only been supported by a floor joist?

 

My previous 1930's house was like this. The downstairs wall was about 1/3 the span from front to back. But upstairs a brick wall that separated two bedrooms meant a lot of weigh supported mid span by the floor joists.

 

When I bought the house there had clearly been a lot of movement, the bend in the floor was clear to see and a door frame was very out of square.  The surveyor noted it was at the limit of acceptable deflection and if further movement was noted a steel beam should be inserted under the wall to support it.

 

In the 13 years I was there it did not move any further. As part of the work I did on the house, I re fitted the door frame and made it square. The plaster did not crack again and when i sold it, there was no mention of it at all on the buyers survey.
 

 

No confusion there, I had previously established the floor joists were squiffy as a result of the recent work. 

 

Now I realise the wall has been made squiffy during the same work because it is supported by a wooden joist that has been affected just like the floor ones. It has been like this for nearly a year so something is holding it up. However I risk making it worse if I just go in and fix what I thought was the problem. At this moment in time I am not prepared to just let it be as it was not like this before and the floor does need fixing (without affecting the wall)

[daiking]

6 minutes ago, Declan52 said:

The inner leaf is more important as it carries the roof. Shouldn't be any gaps in any wall. If it can come down i think you will have to bite the bullet and replace with stud.

 

I had thought about this but initially dismissed it as throwing out the baby with the bath water but trying to move half a tonne of wall with dodgy plaster back up from whence it came does not sound easy either. 

 

Also I am going to need to go back to brick on these wall to replaster. At least if I remove the plaster I will be able to see any more hidden nasties

 

Holes?

 

 

Edited October 10, 2016 by daiking

[Declan52]

The only holes there should be in any walls are for doors and windows.

Get the bolster out and start hammering.

[daiking]

7 hours ago, Declan52 said:

The only holes there should be in any walls are for doors and windows.

Get the bolster out and start hammering.

Luckily The old stuff comes off in large pieces so a crow bar or spade does the job nicely (and quick)

[daiking]

Had a builder round this morning to have a look. Seems like I'm on the same page. Replacing the wall with a stud one was suggested.

 

Something else mentioned was 'meshing' the brick work. In response to the 45 degree plaster crack in the wall to the left of the window and the corner of that wall and the dropped wall. We were all surprised about there being no obvious cracking in that corner but won't know for sure till the plaster is off this weekend.

 

He (weirdly we have exactly the same name) will get back to us.

[daiking]

Had a dirty weekend stripping the plaster off the walls which left me none the wiser. I'll get some pics laters. Still none the wiser as to what exactly is the issue, no smoking gun. Despite the wonky post-build door frame the horizontal mortar joints are still actually horizontal. However,

 

The packing of the existing wall to sit on the steel beams is atrocious with gaps everywhere and I would like it tidied up.

 

The only major sign of anything in the brickwork is below the window, running at sill height in the left corner down to the floor at about the middle of the window. Jagged crack following the mortar line. Around about 2mm in width so nothing scary.

 

Still no evidence in the plaster below the steel beams to indicate any serious issues with deflection or movement. A few <1mm wide cracks along plasterboard and edge bead joints you would normally say were drying out cracking.

[daiking]

Window

Before 

After

Bad mortar jagged crack presumably due to poor packing but nothing untoward on the left hand wall in that corner. Despite the bad packing

The wonky wall

Before

After

Not so wonky it turns out. These mortar lines are nominally horizontal.

[daiking]

For gawd sake I hope those pictures are visible not just to me.

[ProDave]

Pictures appear fine.

 

The wall with the window, the big problem appears to be half the bricks missing on the bottom course. Replace those and pack well and re point the cracked part.

 

The wall with the door, that pocket of blockwork is supported by the door frame and not even keyed into the rest of the wall. I would remove those blocks above the door and replace that bit with studwork and plasterboard.
 

[Onoff]

Toolstation have a mortar gun on offer at the mo. £16 I think with loads of attachments.

[daiking]

2 hours ago, ProDave said:

Pictures appear fine.

 

The wall with the window, the big problem appears to be half the bricks missing on the bottom course. Replace those and pack well and re point the cracked part.

 

The wall with the door, that pocket of blockwork is supported by the door frame and not even keyed into the rest of the wall. I would remove those blocks above the door and replace that bit with studwork and plasterboard.
 

 

That's pretty much where I'm at. I need to make one more exploratory penetration in the ceiling below to confirm the condition of the joist supporting that wall. But so far its looking pretty good.

 

47 minutes ago, Onoff said:

Toolstation have a mortar gun on offer at the mo. £16 I think with loads of attachments.

 

Why do I need that? A spoon would do.

[Onoff]

Seriously mortar guns are great. One top tip though, ONLY use soft sand mortar. I tried a sharp sand mix and cracked the barrel! Fixed now with lashings of duct tape and still going strong.