floating floor joist advice/ventilation issues

[yorkney]

Hello,

First time on here and hope that I can get some advice from the experienced. The ground floor living room has a cellar underneath, a bearer wall separates the the cellar storage area from the other half which has been filled with rubble and soil.

I have now found the ends of three joists which rest on a wooden sill under the kitchen entrance have rotted. I also found two bricks pushed under there (maybe to stop the material used for the kitchen floor from escaping?) This whole lot was covered in soil, so stopping air circulation. What could I use to replace the bricks? Air bricks maybe? Plastic or clay?

I was initially going to use a metre of c24 timber 50mm x 125mm and marry it to the the rotten end of the existing joists (which span 4 metres), but then I thought that I could use a 2 metre length with one end on the bearer wall and the other end on the sill under the kitchen door. Is this ok to do? What size coach bolts and how would I space them? All advice gratefully received and thanks for taking the time to read my long winded situation.

 

[pinenot]

A wee sketch please yorkney, and welcome...pinenot

 

[yorkney]

Thanks pinenot. Would pics be better?

 

[pinenot]

Yes! pics would be fine, although they will not show the whole picture or dimensions they will provide some reference...pinenot

 

[yorkney]

I hope the following images help


[GALLERY=media, 63327][/GALLERY] [GALLERY=media, 63329][/GALLERY] [GALLERY=media, 63331][/GALLERY]

The first image shows the joists , the second image shows the cross section of the kitchen floor, this material I can rake out quite easily and the third shows some of sort of clay pipe which is just to the right of the third jost and this clay pipe runs under the cellar stairs.


Thanks for looking

 

[pinenot]

If the first picture of the joists is the ones with rot you have described, there could be a simple solution of building a new section of sleeper wall the they are sitting on. I suggest this as those joists look in very good condition and don't look as if they require anything other than a good dousing of wood preservative and the damp problem corrected of course.
Start by digging down to solid ground/foundation and build a with a dpm between the existing sleeper wall and the new section, having treated the joist ends first. Then you can dig out the ground at the other side of the door, exposing the problem and correcting it in the best way possible.
Contact any local road builder to ask if they have any vertical drainage sheets/odd bits available, putting this against the external wall when your back filling with some perf pipe(led away from the building to a french drain/sewer) at the base should resolve the penetrating damp and the treated joist ends should remain fine, supported on good sections...pinenot

 

[yorkney]

Thanks pinenot, those pics aren't very good, these should be better [GALLERY=media, 63383][/GALLERY] [GALLERY=media, 63379][/GALLERY] [GALLERY=media, 63330][/GALLERY] [GALLERY=media, 63380][/GALLERY] [GALLERY=media, 63381][/GALLERY] [GALLERY=media, 63380][/GALLERY]

The three joists are rotten at the ends, in the foreground of where the joists are rotten is the cross section of the kitchen floor. The clay pipe is something that I was curious about, what could it be?

My original idea was to marry 3 x 2metres lengths to each joist, one end of the new joist sitting on the sleeper wall, this is the fifth pic clockwise and the other end sat on DPC where the wooden sill has deteriorated. For a 2 meter span of new joist married to the old one, how many coach bolts, sizes, spacings would be a necessity.

Where the old joists have rotted could I put a few arirbricks in there thus allowing ventilation and also stopping the kitchen floor material from moving?

There are no external walls, they are all internal ones.

Thanks

 

[pinenot]

Right! first things first, can you put rods down that drain pipe ans see if they are attached to you waste system? it may have been a drain for an old toilet?? and what were looking at could be the dry end. Best to be sure though, if thats where the damp is coming from and it's connected to the drainage layout, then that wouldn't be good.
Can you explain what you mean by keeping the kitchen floor material from moving? my guess is your referring to the solum (compacted inert infill under the joists and between the brick walls???)...pinenot

 

[yorkney]

pinenot

I'll investigate the pipe. Your guess is correct regarding the solun. What are your thoughts on marrying 2 metre timber to the old joists? I just want to be sure what I am going to do is safe.

Thanks for reading

 

[pinenot]

Before slicing (marrying) any timbers onto the existing joists, it's essential to have the moisture problem resolved first.
You say the area affected is internal which would suggest a leak of some sort, I'm afraid installing air bricks would be of little use. So let's see first if that drain is a problem. Are there any water pipes in the vicinity? now that the affected area is exposed is there any unusual smell associated with the damp?? are the rotted joist ends, apart from damp, discoloured in any way??? ...pinenot

 

[yorkney]

Pinenot

The joists do not seem discoloured, there isn't an unusual smell and there aren't any pipes really close by. The water pipe is about 6ft away and I have that exposed and have not noticed any leaks. Could the fact that the joist ends were covered in soil and rubble encouraged the rot, the wood at the end of the joists just fell away, very mushy. The clay pipe is as dry as the proverbial, it seems to run through the cellar wall under the cellar stairs towards the other reception room, could this pipe be some sort of attempt at air circulation between the two reception rooms?

I appreciate your advice and interest in my problem, thanks.

Once the damp problem has been sorted, is my idea about splicing a good one? It's just that my wife is doing my head in, the room is a mess and with two little kids is a nightmare.

 

[tony1851]

Maybe the clay pipe was for ventilation between one under-floor void and another?

 

[yorkney]

tony1851 great minds.....

 

[dann09]

1. Can you indicate which floors in your house are suspended and which solid?

2. Can you gain access to other sub-area's? You really should crawl the whole accessible sub-area and probe for rot and soil contact.

3.Be extremely cautious in working under the kitchen door threshold, if you disturb it or the frame then you will have a whole other issue on your hands.

4. There appears to be a wooden plate under the joist tails, most probably its rotted too, and will have to be totally removed. Any plates in any other area of the house will have to be carefully examined.

5. The solution to the joist tails is to cut them back beyond any sign of discolouration, and then bolt-on new lengths approx 1m longer than the offcuts.

6. Treat the ends and cap them with DPC material. Then wedge them up to the underfloor.

7. What ventilation do you have in the area in question, and at the exterior walls?

8. Do not attempt any wall re-building or "splicing".

9. This might be a job too far for a DIY'er, but if you are handy with power tools in confined spaces then have a go. Come back here if you want walking thro it.

 

[dann09]

This thread would do better in the building forum - the mods will transfer you if you ask.