victorian terrace floor

[garethraper]

Recently lifted the floor in our victorian terrace after a boiler leak and discovered a lot of damp and rot in the joists. Pretty sure the boiler leak isnt the underlying cause. The external ground level is higher than the internal floor level and heavy clay. There is a poor, brittle, hollow concrete oversite which seems to be serving no purpose. Have been contemplating options
1) replace wall plates on sleeper walls and include dpc, ensuring no direct contact with walls
2) as above but replace concrete oversite with new oversite over a vapour barrier
3) as above but use concrete beams and blocks rather than wood, maintaining underfloor ventilation
4) completely solid concrete floor with insulation layers and screed

Any advice very much appreciated.....going round in circles at the moment

Thanks

 

[ree]

Why not post pics of underfloor, the room(s) and external?

 

[garethraper]

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[garethraper]

Hi Ree - thanks for showing and interest!!!

Have been trying to read as much as I can about the possible solutions but there are lots of conflicting opinions varying between open ventilation and sealing everywhere is vapour barrier.

Concerned that this house will always have damp under floor boards which airbricks alone wont keep below acceptable levels - dont want to do a load of work on a wooden floor only for it to go rotten in a few years. Looks like the current floor was replace only around 10 years ago although the builder didnt use any DPC over sleeper walls, bridged the woodwork and external walls with lots of dirt and debris and also managed to block the airbricks....

Concerned that adding a membrane and more robust oversite would stop the damp directly in the floor but may force more damp up the walls? Also concerned that this additional weight may also contribute to subsidence???

Concrete joists rather than wood seems a logical approach - again would welcome any views and advice on insulation/ventilation

A modern solid floor with integral insulation layer may be another option but guess this removes any ventilation from the walls (issue or not?). Also concerned about services entering property which would be above an oversite and below floors, similar for internal electrics and central heating - little reluctant to bury pipework - guess the electrics could be chased above the floor

Ultimate aim is to add extension in the side return and a loft conversion so if any option provides better structural support for this it will have advantages. Similarly, floor considerations for side return. guess taking the floor level right down would reduce the damp issue in to lounge but how to stop it at the edge of new extension? french drains?

Some of the internal walls are built directly onto the floorboards without direct support from sleeper walls. Was considering putting strong foundations under these and building up structural support as this looks like an area of potential failure in future so would want to sort this while the floor is up - any advice?

Thanks for any help




1) photo of outside showing foundation depth, ground level and level of airbricks
2) showing yard in side return, all cracked and pipes from kitchen/bathroom into drains
3) space under floorboards, some parts of sleeper wall removed and wall plates removed (as not stable and rotten), shows depth of current floor space under joists. cant really see but airbrick entry is just below plaster level, airbricks outside are above the skirting board level (removed)
4) view under floorboards, very damp, debris from previous builder (chimney breast removal) still there, lots of earth
5) view under floorboards, lots of damp debris, the white stuff in later photo
6) white gunk, looks dry and crystaline in photo but is very wet creamy paste when touched -WHAT IS THIS???? doesnt smell of anything...was expecting it to smell mouldy but doesnt
7) photo (sideways) of fireplace hearth. note damp patch in surface (doesnt dry out) not sure if coming from below or from wall where chimney removed and possibly letting rain in from roof....??

 

[ree]

Thank you for the pics and information. It really helps when you discuss the pics.
Could you post more pics: of a side view at ground level of pic 2. and a general view of the rear of the house (indicate where you propose an extension)?

pic 1. the GL could do with being dropped by 150mm to a finished surface. But, this could be difficult to achieve, and the neighbour's yard must be taken into account?

pic 2. As above, drain hoppers would have to be lowered as well.

pic 3. high air bricks are useless for venting the sub-area unless they are sleeved down to the interior below the floor.



pic 4. all the wall plates should be replaced by new plates with lengths of DPC material shielding them from masonry contact.
Any rotten joist tails will need cutting off & replacing.
What is the pipe for?

pic 6. Its crystallised salts - harmless.

pic 7. Crack out the old concrete hearth and dig out the soil to below the perimeter plate level. DPC protect the plates and bridge the gap with infill noggins, & then board over.

My views are to joist and board over the floor and lay a membrane across the oversite. Given good thro ventilation from back to front of the house to be provided. This would be the most expensive option but would help with extension options/possibilities.

Replace all airbricks with plastic 10" x 6" airbricks.

The floor(s) could be insulated with ease.

Which walls are unsupported?

Where else in the property is damp manifesting - "in the lounge"?

Crawl the sub-area and probe all joist tails seated in, or near, walls.

Remove any wood debris from the sub-area.

FWIW: are you confident in the support for any remaining c/breast? Perhaps pics of the c/breast or c/stack?

 

[garethraper]

Thank you very much for your time in posting a reply

I will take more pics and post as soon as I can. Extension woud be L shaped extending 3m out, full width of property and back down side return.

What are the difficulties in lowering the side return ground level? Agree neighbours yard may be problem but would be looking to erect a party wall (foundation depth??) As part of extension plans. Would mean dealing with waste water drains.

Will replace airbricks with the plastic telescopic type

The pipe is gas service pipe

Could you explain the reason for reinstating the wood floor rather than any of the other options? Do you think that the damp problems would be resolved if the ground was lowered and ventilation improved? Surprised to hear this was the most expensive option...... ? Also you mention this may aid future extension, in wha way?

There are 3 internal walls.

Stud partition wall between 2 reception rooms. This is on top of floor boards and perpendicular to joists. Joists above wall plate above 2 course sleeper wall with occasional gaps for ventilation between front and back. This stud wall I presume replaced a brick & timber frame wall. Concerned this will have been providing support to the major wooden beam above which supports the first floor and now putting more pressure on the other internal walls causing sagging.

Brick and timber wall between back lounge and hallway, on top of floorboards, parallel to joists. Joist supported by another joist running perpendicular half way across the room, this supported by periodic brick pillars. Similar with the wall between the front lounge and hallway.

The whole sub floor is damp. Its been opened up for 2 months with fans and dehumidifierbut still very damp. Dry patches emerge but when fan and dehumidifier stopped the damp seeps back. Seems to be coming from all sides.....

Will get damp wood probe for joists

The chimney breast was removed right up into the roof. Difficult for me to judge if done ok. In the roof the original chimney seemed to merge into the party wall rather than being straight up all the way (if that makes sense). Is there an easy way to tell if the damp in the hearth is coming from the chimney?

Thanks again for all your help!!!!!

 

[ree]

If you dont mind, I'll answer after seeing fresh pics. Anything you have questions or doubts about then pic and post it eg. the loft c/breast, the possible knock-thro/sagging etc.

One thing, is that live gas pipe a steel pipe?

 

[garethraper]

Apologies for the delay in posting - its been a tough week!

yes, the gas pipe is a steel pipe

pictures added but difficult to see any sagging or uneven levels in these

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[garethraper]

1) &2) first two are side views in the side return. ground level here is above ground level in kitchen, concrete is poor and cracked, definite leaking over top of trap and join between floor and wall will let surface water in. Expect this is main source of damp into kitchen floor but internal wall seems damp for most of height under window. pipework or other holes could be letting in water.

3) damp in 1st floor ceiling, the joists above are in the bottom right of 11th photo and show some damp but not obvious from where. The roof valley is above this area and could be source.

4) floor of reception room facing into kitchen and side return window. Looking to fit downstairs toilet understairs in hallway (out of shot to right) with pipe running with a large sweeping bend from right and into side return to join existing soil pipe.

5) wall where plaster showed large damp bloom. bathroom leaking in floor above but other side of wall, joists above kitchen soaked and leaching through brick and absorbed by plaster. damp in archway wall doesnt seem to be drying. Am assuming this is due to bathroom leak but want to ensure not due other potential source eg exit of toilet pipe into side return.

6) hallway wall. presume dark stain in joist is damp treatment? note unsupported bricks, difficult to see unsupported wall underneathfloor (see photo 7)

7) under hallway wall. thinking of digging deeper foundation under this wall, providing alternative temporary support and removing bricks, replacing with honeycomb wall of engineering bricks

8) back of knocked out chimney in roof space. filled and rendered above where it tapers into party wall. not sure of status above - concerned it could be source of water ingress which goes down wall below.

9) several more recent (15 years ago) bracings for roof, top ridge beam had split.

10) wall plate. not sure if this is normal gap for ventilation or whether the roof has splayed a little as the ridge sagged.

11) roof timbers seem damp below valley

12) chimney above back bedroom removed but left partially removed in roof space. chimney is shared with neighbour. Would prefer to dismantle completely, removing chimney stack and pots but would require nieghbours to do same and suspect they woudlnt want to. Alternative to support more directly?

13) front of house, some flashing missing from bottom left of roof, gable (as neighbours) removed and replace with flat roof above bay - likely source of leak. would prefer to replace the gable structure.

14) under floor in front room bay, patch drying near airbrick but like this for long time, rest doesnt have signs of drying improving

Many thanks again for any advice!

 

[garethraper]

1) &2) first two are side views in the side return. ground level here is above ground level in kitchen, concrete is poor and cracked, definite leaking over top of trap and join between floor and wall will let surface water in. Expect this is main source of damp into kitchen floor but internal wall seems damp for most of height under window. pipework or other holes could be letting in water.

3) damp in 1st floor ceiling, the joists above are in the bottom right of 11th photo and show some damp but not obvious from where. The roof valley is above this area and could be source.

4) floor of reception room facing into kitchen and side return window. Looking to fit downstairs toilet understairs in hallway (out of shot to right) with pipe running with a large sweeping bend from right and into side return to join existing soil pipe.

5) wall where plaster showed large damp bloom. bathroom leaking in floor above but other side of wall, joists above kitchen soaked and leaching through brick and absorbed by plaster. damp in archway wall doesnt seem to be drying. Am assuming this is due to bathroom leak but want to ensure not due other potential source eg exit of toilet pipe into side return.

6) hallway wall. presume dark stain in joist is damp treatment? note unsupported bricks, difficult to see unsupported wall underneathfloor (see photo 7)

7) under hallway wall. thinking of digging deeper foundation under this wall, providing alternative temporary support and removing bricks, replacing with honeycomb wall of engineering bricks

8) back of knocked out chimney in roof space. filled and rendered above where it tapers into party wall. not sure of status above - concerned it could be source of water ingress which goes down wall below.

9) several more recent (15 years ago) bracings for roof, top ridge beam had split.

10) wall plate. not sure if this is normal gap for ventilation or whether the roof has splayed a little as the ridge sagged.

11) roof timbers seem damp below valley

12) chimney above back bedroom removed but left partially removed in roof space. chimney is shared with neighbour. Would prefer to dismantle completely, removing chimney stack and pots but would require nieghbours to do same and suspect they woudlnt want to. Alternative to support more directly?

13) front of house, some flashing missing from bottom left of roof, gable (as neighbours) removed and replace with flat roof above bay - likely source of leak. would prefer to replace the gable structure.

14) under floor in front room bay, patch drying near airbrick but like this for long time, rest doesnt have signs of drying improving

Many thanks again for any advice!

 

[garethraper]

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1) rear view. Looking to add extension full width of garden and down side return, replace party wall to left, add new party wall to right, 3m depth from existing kitchen wall. layout still undecided, comments welcome - tempted to keep existing side wall as an internal wall (at least partially) leaving a galley down side. Expect to nee to move/reconstruct inspection chamber further away from house. roof likely to e slate and velux. loft conversion would be rear dormer, not sure if best to build up party walls with dormer between or just build up dormer stud walls. plan to reroof with slate (as prefer look and to reduce weight)

2) under floorboard where central heating tank had been leaking - only area that seems to dry. this dried out very quickly but the damp outline has been same for over a month with no sign of improvement

3) stud wall between 2 reception rooms. floor slopes down from right to left - maybe an inch over width of room


many thanks again - if any more photos required please let me know!!

 

[ree]

Your project has to be dealt with as a whole - each item seems to be leading into the next two or three items, & so on. Your project can be partly realised by a DIY'er but professional help must be input at this stage or you will be confounding yourself, and it could be quite expensive to be going back over work.

Why not make a list of everything that you would like to see done - everything!
Then call in a local builder(s) for a view on site. Write down everything that they say - the extension for instance will need drawings. But plans cannot be drawn up until its clear exactly what is to happen in the main house.

When the roofs are stripped, the total roof framing will most likely have to be re-built/re-fixed. Parapets will probably need attention at that time.

The remaining c/breast in the loft must be properly supported according to local Regs - its dangerous.

The metal gas pipe needs a careful examination for any rusting or perishing.

A new groundworks plan for the waste and soil pipes will have to be worked out and all CI replaced.

While its accessible, the red paint should be removed from the brickwork.

Dont dig under any wall - leave that to professionals.

Wherever c/breasts have been removed the flue sooted walls should be cleaned and rendered in lime and sand - gypsum plaster will fail.

Start talking Party Wall possibilities with neighbours now - dont wait. Discuss all your propositions with them, dont wait for issues to arise.

 

[garethraper]

Thanks again for all the advice - certainly makes sense
We did bring in several builders to give their views and provide quotes when we first bought the place and it was basically a fortune just to do cosmetic work. None suggested there was any potential issues with the property (which seemed obvious to me hence the investigations) which left me a little jaded....
I guess I am trying to get as informed as I can before calling in the professionals and get closer to our final plans (still going round in a few circles) but at least get things straighter in my own head.
Planned the next step to call in structural engineer and take it from there.
I wouldnt dig under the wall without getting professional opinion and presumeably building control approval - the wall in question is only supported at either end of the room on the sleeper walls plus by another cross joist across the middle so on direct support from the floor underneath along its entire length - was just speculating whether a foundation with new brickwork support would ultimately be the way to go.
is there any particular method of stripping the paint or brand of remover you would recommend?
Also, you comment about the lime render, is this due to breathability or something else?
Thanks again for all you time and advice.....very much appreciated!

 

[garethraper]

Thanks again for all the advice - certainly makes sense
We did bring in several builders to give their views and provide quotes when we first bought the place and it was basically a fortune just to do cosmetic work. None suggested there was any potential issues with the property (which seemed obvious to me hence the investigations) which left me a little jaded....
I guess I am trying to get as informed as I can before calling in the professionals and get closer to our final plans (still going round in a few circles) but at least get things straighter in my own head.
Planned the next step to call in structural engineer and take it from there.
I wouldnt dig under the wall without getting professional opinion and presumeably building control approval - the wall in question is only supported at either end of the room on the sleeper walls plus by another cross joist across the middle so on direct support from the floor underneath along its entire length - was just speculating whether a foundation with new brickwork support would ultimately be the way to go.
is there any particular method of stripping the paint or brand of remover you would recommend?
Also, you comment about the lime render, is this due to breathability or something else?
Thanks again for all you time and advice.....very much appreciated!

 

[ree]

Paint stripping from brickwork can be done with "Paint Stripper" applicatons - there's even a formula somewhere for making up a DIY concoction but its best to ask advice from Paint forums or web sites.
Paint stripping pads chucked into drills will remove stuff but must be used carefully.

Lime render works, so does lime,cement and sand but lime render is best. Wire brush all traces of soot if possible.