Help fixing floor joists and damp in Victorian house

[nitch]

Hello,

We bought a Victorian terraced house last year. We knew about problems in the front room with damp and that the floor wasn't level and we're finally getting round to trying to rectify the problems. The bay window was quite damp with salts coming through and soft plaster.

What we've done so far:

1. Removed a concrete slab from the front which was restricting the air bricks and installed air bricks at the correct level
2. Fixed the guttering as water had been running down the external wall, probably for many months/years
3. Repointed the outside of the house
4. Had some work done on the chimney to fix some holes on the roof
5. Lifted half of the floorboards so far to inspect and clean
6. Removed the bricks that the end of the joists sat on in the alcove closest to the external wall as very damp and loose

Problems we've found:

1. Rotten joists, especially in the alcove closest to the external wall and some rotten boards that the joists sit on.
2. Soft, damp plaster
3. There is some kind of crusty coating on the floor that has failed in many places so damp earth is on show
4. Sleeper walls not in great shape

Some pictures:

We're going to fix the joists that need doing but I've got a few questions:

1. At the moment the joists sit on the brick sleeper walls and then a piece of wood between the brick and the joist. Should there be a damp proof membrane between that piece of wood the brick? If so, is that just a sheet of plastic?
2. Would you recommend rebuilding the sleeper walls?
3. Should we put a layer of concrete on top of the earth/crust that is currently there?
4. Should we DPC the sleeper walls?
5. I'm planning on using the damp proof cream on the external walls - is that the best stuff to use?
6. Is there anything else we should be doing whilst we have the room in this state?

Many thanks in advance for any help or advice you can give

 

[pinenot]

I would want to replace that concrete beam/block under the window with proper brick work.
To answer most of your concerns/questions, dpc should be fitted wherever wood meats brick, joist ends that go into the brick walls are best wrapped in dpc, so if your replacing any do that. Sleeper walls are seldom pretty in my experience, so as they say "if it's not broken don't fix it" use your own discretion on that.
Do as much rewiring (extra plugs etc.) whilst the floors up and insulate between the joists, I favor rock wool laid in draped & stapled nylon mesh, because it can be packed into the narrowest of gaps ensuring you leave no cold spots, also it will allow some circulation of air from the air bricks you mentioned, to keep everything sweet.
You could pour in some liquid dpm over the damp spots of the solum, the rest has proven itself over a long time so leave well alone I say...pinenot

 

[nitch]

Thanks for taking the time to reply.

I'm definitely going to fix that part under the window. When we took the plaster off, bits of brick and rubble and old mortar just fell out hence the big holes.

We hadn't really thought about insulating under the floor but obviously the best time to do it so will look in to that.

The liquid DPM - can I just pour that all over the floor and straight on to the earth or will I need to put down a layer of concreate first? Also can I just paint all the brickwork to stop salts coming through?

Thanks again

 

[pinenot]

Salts will eventually come through whether you paint them or not, a good brush off and wash with bleach will do as good.
If you use an epoxy based liquid dpm you can incorporate fiber matting over the worst bits, just make sure the liquid dpm you choose is tolerant to slight damp and spread it until it cover 400 mm or so onto sound adjacent areas, that should do it...pinenot

 

[dann09]

nitch,
If you are interested, i could point out a few things, and perhaps take you a little further.

 

[nitch]

Hello,

Any further help or advice would be really appreciated.

Cheers

 

[pinenot]

I think a lot of what you have already done i.e. fixing the rainwater leaks, re-pointing and reinstating the air flow will need time, but unless there is a water problem around your land footprint anything else could be throwing money away. Just my opinion of course...pinenot

 

[dann09]

When replying its quicker (if not cut & pasting a quote) to simply refer to the item number.

1. Are the floors suspended floors, except for the kitchen?

2. Do you intend to lift all suspended floorings? Any knock-thro's or c/breast removals anywhere. Smoke test & sweep all flues.

3. Have you sorted out ground levels (GL) ref the FFL's? Ideally, GL should be 150mm below any DPC.

4. Can you post pics of the front & rear exterior showing air bricks.

5. Have you located the source of the over site (solum) water? Do the neighbours report a water/damp problem.

6. Have you located and tested your internal & external stop taps. Is the water service pipe in plastic & where does it enter the property?

7. Do you have, or want, central heating? Your fire surround with inserts looks great.

8. Is the bay a single story? Have you examined the bay roof?

9. De-nail all boards & joists -buy a cheap nail puller. Dont beat the nails down in the joists, remove them.

10. If you wished, now that your boards are up, you could sand them with a belt sander, the backs might be in a better condition than the tops.

11. The above reference to "replace that concrete beam/block under window with proper brickwork."
They are the original stone window cills - why would you want to replace them?

Merely brick up below the cills, and in any vertical side pockets, dont move any supporting bricks or mortar. Let the S&C set.

Use slate wedged into S&C, or plastic packers if you have them, to stabilise the frames.

When everything is settled, with all sashes closed, remove the wood packers - wood might fungal rot like the joist ends.

12 The PVC frame fixing is not of the best but i should leave it be - check the exterior frame caulking.

 

[dann09]

I've split my post into two less you go comatose reading it.

Correction to Item 11. Dont remove the wood packers, leave them alone. I was thinking of something else.

13. You have a capped off gas pipe in 15mm copper. Is this pipe still live?
Was your gas installation tested on moving in?

14. You test the joists for fungal damage by driving a slot screwdriver, or similar, into suspect wood.

Test all the sleeper wall plates. Probe up from the bed mortar.

If rising damp is present then DPC's will have to be used below the plates.
DPC's will have to isolate all joists sitting on ledges, or tight to brickwork.
DPC is a black plastic that comes in rolls.

A number of your joist ends are obviously damaged & require cutting off 300mm past signs of damage.

15. All the joist tails that are presently sitting in the wall pockets will be fungal damaged.

You will have to cut the tails out, and bolt-on new joist ends ( research bolt-ons on here), or sister the tails to sound, securely landed joists.
Neither the sistered pieces, or the bolt-ons, must creak or squeak.

Test all joisting before boarding back over. Test for movement, bounce & squeaks.

Some of your joists are sistered now, indicating past remedial work.

16. Joist tails that sit in the wall pockets have to be mayonnaise (fungicide) treated and capped with DPC material.

17. Moving air (cross ventilation), is required especially in c/breast recesses and front wall to rear wall. Too thick an insulation in the floor will obstruct the air flow at sleeper walls.

18. Ideally, your sleeper walls should be honeycombed for air flow.
The RH chimney breast recess, obstructing sleeper wall should be opened up a little.

19. All cables and pipes should be securely clipped to the joists

20. You should be able to crawl the whole sub floor after boarding over. An access trap should be cut.

21. Dont use any form of damp proofing cream or similar. A waste of money, and the external injection holes look terrible.

22. Rendering the walls with a 3:1 mix of sand and lime, or a 5:1:1 of sand and lime and cement will hold back salts and damp for 20 years or so.

23. Instead of a metal corner bead you have a timber batten at the bay return - you should remove that wood and the plugs that its nailed to. Dont leave any wood in the external walls.

 

[nitch]

Hello,

Many thanks for your detailed response. I've tried to answer any of the queries below along with some more questions!

1. Yes, the front room, dining room and hall way are all suspended. Kitchen is concrete.

2. We might knock through from the dining room to hallway but unsure yet. We're pretty certain that we'll keep the front room as one room. At some point, the rest of the floorboards might well come up across the ground floor. The chimney in the front room has been swept and smoke tested by us and seems ok.

3. I'm afraid I don't understand this one

4. Here are some pics of the front air bricks. Note, the one on the left is currently blocked so that's on the list to be fixed.

I don't have any of the back of the house as we haven't really explored that yet.

5. I think the problem was water running down the front of the house due to broken guttering which has been fixed. I will ask the neighbours to check if they have any problems.

6. I think the water is ok. There is a stop tap next to the front door that seems to be in good working order.

7. Central heating is installed and and working. Boiler was serviced a few months ago. Point 13 asks about the gas pipe. We removed the gas fire and had the pipe capped professionally and intend on fitting the fireplace that is pictured.

8. As you'll see in the pictures, the house is double bay. We have already done some work in our bedroom upstairs and external wall was good

9. I've pulled out most of the nails. Every single one was rusty.

10. We're thinking about sanding the floorboards as we've done upstairs but it's a horrible job. We're quite tempted to keep it as quite a nice warm room as we may open the back of the house up so we may carpet. Some of this will depend on how level we get the floor

11. I agree about the cills. I'll try my best to make them good. We removed the nasty plastic threshold covers that window installers seem to like to use to cover up gaps and we want to plaster right up to the windows. Shall I just fill the voids with brick or should I use a wooden frame to attach the plasterboard?

12. We think the caulking is ok

13. See 7.

14. The sleeper plates at the joist ends were rotten but most of the others so far look ok

15. Once I get the rest of the floorboards up I will check all the joists carefully and replace or sister/bolt-on where required. Getting it all level will be quite difficult I imagine.

16. We will definitely be doing this

17. Do you recommend not insulating?

18. Some need rebuilding so will do this or try and remove bricks from current walls

19. Will do

20. Really? You'd have to be pretty small!

21. The damp proofing cream by Safeguard is injected from inside so covered by the plaster but it is expensive stuff although I could do it myself.

22. Thanks

23. The only problem with this is that we'd have to take all the plaster off the external wall. Do you think we would get away with cutting the wood to the level we are at?

One thing I'm still confused on is what I should put down directly on to the ground to seal out the earth?

Many thanks again for all your help.

 

[dann09]

In general,

the concrete path surrounding the bay could do with lifting and the GL lowered.

You could replace it with gravel and dig a little trench by the wall and fill with stone.

The S&C plinth is pulling up moisture & could do with being hacked off - however, perhaps just hack off the bottom 40mm to break ground contact.

Ideally, install perhaps four 10" x 6" air bricks in place of the in-situ.

3. see above, FFL means finished floor level - with respect, suggest you pick up speed on building terms & abbreviations.

Do you have air bricks under the front door step?

5. Do you today, still have water in the sub area?

6. You must be certain. Locate & test the external stop tap and ID the pipe material.

7. None of my business, but i do hope that you are retaining the CI insert fire surround.
All fires & stoves now require a raft of Regs. research on here.

11. Dont use any "wood" in the bay reveals or wall. Ref W/F see below.

15. Setting joists is simple with a string line & three equal blocks - google for the method.

17. BCO (if involved) will insist on Regs. floor insulation. But make certain that its not blocking joist bay ventilation at air bricks or over sleeper walls.

20. Go under the floor, & see if you can crawl.

21. Be my guest.

23. Then cut lower portion above rusting nail, & remove its packing from the bed. Drill & plug & screw the loose end.

24. Screw boards down, dont nail.

25. As boards are lifted they should be crayon marked for position and location - it will aid relaying.

26. W/F (window frame), brick in all surrounding voids, except between the cill and frame. Use a semi-dry mix of S&C to pack in there.

 

[lovelyjob]

May I say thanks to all that replied to nitch...pinenot, dann..what very helpful guys you are. At this very moment in time I too have one of my floors up and below looks very similar to Nitchs'. I will re read the whole post to try to take it in. I may have a couple of queries so I look forward to your advice and experience. I'm a novice at this and staring down at bare earth, sleeper walls and such-like was a bit of a surprise . Will post some photos to view as I have some queries about the fire breast and how to tackle the hearth. The house is a 100 yr old Victorian terrace by the way. Nitch...if your around, did you take any progression photos at all? Thanks again. Regards, Shimmy.

 

[nitch]

To be honest, I haven't progressed from there yet...except the floorboards in the hall are up with more rotten joist tails. I've been concentrating on clearing everything out and making sure the ventilation is adequate and working first. Then I need to start thinking about sorting the sleeper walls and joists...

We've also just cleared out the dining room so about to lift the floorboards in there as well. We live upstairs now. Possibly for good.

Once I get somewhere, I will update. All the best