Wet Rot Issue - Dropped Floor

[arh]

I have a wet rot issues with the joists in my living room. As per the pictures they are damaged and the floor has dropped. Floor is normally covered by laminate. My house sits lower than the road and the driveway slopes towards the house. Looking under the floor I can see some slight wet/damp patches. I was visited by a damp company and confirmed that it was wet rot and just the timber needed to be replaced without any treatment.

Can anyone give me some advice on the following:

1) Should I spray some wet rot treatment on the new and old timber to be safe?

2) What is the best way to attach the new joists to the masonry wall? Joist hangers, timber in brick, hang off ledger beam?

3) What is the best way to join the new joists with the old ones?

4) I have read that it is best to cover the ends and the ledger beam with DPC. What is the best way to stick this to the wood?

5) How can I prevent the natural ingress of water from the higher driveway under the house. The drive level is below DPC but the driveway is very old tarmac and will be replaced soon. IT has surface cracks which is why water may be travelling down.

6) Should I seal the inside wall or use a DPC or maybe inject a damproof course under the joist level? Should I use cement ot bock and ovious cracks/holes?

7) Would it be worth adding some additional air vents?

8) Is there a fan that I can fit under the floor that will help with ventilation/damp?

9) A damp company has quoted me £2.5k - does that seem fair? Would I be better off getting a normal builder to fix this? They have said that they will give me a 20 year guarantee.

Thanks and sorry about the no of questions.
Pics are below.

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• arh
• 5 Feb 2014
• 1

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• arh
• 5 Feb 2014
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• arh
• 5 Feb 2014
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Air brick

• arh
• 5 Feb 2014
• 1

Damp proof is at bottom of air brick.

 

[ree]

Before you or anyone else do anything you must be pretty certain as to what is the cause(s).

You will have to lift more boards to expose the floor joisting in the bay, and perhaps further out into the main field of the flooring.
Post more pics when all damage is exposed.
Bolt-on repair joists are best practice.

The rad will have to come off the wall, and the skirting be removed because it is probably rotted on the back.

All the plaster below the window board might also have to be hacked off.

At the right hand side of pic 1 i think that i can see white dry rot strands.

You will need some new 10" x 6" vents. Post pics of the front of the house and driveway.
You might need channel drainage.

The plinth is possibly bridging the DPC, and is in ground contact.

Dont seal or inject anything.

Is the wall a cavity wall?

Where are your joists in relation to the outside ground level?

What works exactly did the damp company specify?

Sack the ext fan idea.

Someone should crawl the whole house and check for rot and ventilation issues.
Note any damp oversite.
Suspended floors need constant cross ventilation.
They should also walk the house perimeter and note location and sizes of air bricks/vents and render ground level issues.

 

[skhudy]

I had a damp company out when a house survey picked up some damp in the extension near a bathroom. DPC failed they said, injection and hacking / replacing plaster, 20 year guarantee. I fixed it myself - a copper pipe embeded in the concrete in the bathroom was leaking vast quantities of water (Water meter have it away).

Anyway that's my experience with damp companies. With all the rain we've been having are you able to see any obvious place water is coming in?

You say your house is lower than the road, usually there is a drain for the rainwater to go into, do you have this? looking at the neighbours drives may help. If it's just running down the drive against your house that is a problem.

Are your air vents clear at the back of the house? the air will vent in one side and out the other. I've read people finding water under their house under the floor boards ( high water table) but this isn't a problem as long as there is ventilation.

 

[arh]

Firstly apologies for the long reply:

My driveway is on a slop towards the house so I suspect that water may be running down as there is no channel drain present. From the marks on the inside wall it appears that water may is getting into the vents?
There is a small drain present but it is not that good,.

I think I should get my driveway replaced very soon as the current one is shot.

The vents are above the DPC but the joists go into the same hole so they partially obstruct the vent? Is this right?

I think I should gets some new vents fitted next to the old one away from a joist. Should I go for standard brick vents or those L shape ones?

There is no plinth as the joist are direct in a hole in the wall. They were completely soaked through. When I fit new ones I will wrap them in DPM. Any particular type that I should use and how far in from the end do I need to go?

Wall is not a cavity wall. Joists are above the ground level and the same height as the vents.

They said the following:
The following infestations and infections were noted:

WET ROT FUNGUS - (CONIOPHORA PUTEANA)

Isolate plates and joists from brickwork with damp proof course felt.
The external ground level appears to be high and possibly bridging the damp proofcourse, this may lead to dampness penetrating the brickwork. We recommend client's own builder lowers external ground level to at least 6" below damp proof course level.

Any advise on how to get rid of the horrible strong musty smell?
I am going to spray to wall and new wood with http://www.lifetimewoodtreatment.co.uk/product/multi_shield.html
Can anyone recommend this or an alternative?

Should I let us dry out with a dehumidifier before I put the floor back?

I am going to use 4x2 treat timber - will these be ok?
http://www.selcobw.com/special-offe...m-x-47mm-4-x-2-kiln-dried-c16-4-8-metres-fscr

What is the best timber to use for floorboards? Should this be treated also?

I previously had a plastic sheet over the floor as per the instructions from my Quickstep laminate. Should I put this back as I am worried that this has made things worse?

Thanks again!

Air brick

• arh
• 5 Feb 2014
• 1

Damp proof is at bottom of air brick.

Front of house

• arh
• 9 Feb 2014
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Driveway is aged tarmac that needs to be changed!

Joist in vent?

• arh
• 9 Feb 2014
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Untitled

• arh
• 9 Feb 2014
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Rotten joist

• arh
• 9 Feb 2014
• 1

These arr soaking wet!

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• arh
• 10 Feb 2014
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• arh
• 10 Feb 2014
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[ree]

Excuse my bluntness but before anything else "Stop smashing your tongue and grooved floor boards."
Check the current price per metre.
Search on here or elsewhere for the simple: how-to lift T&G without destroying it.

You will probably find Chipboard T&G flooring panels as the cheapest replacement. Screw them down.

1. the exterior requires channel drainage across the whole front elevation including the porch and on the left to the boundary point.
The stone abutting boundary or "planter" wall must be pulled back from butting the house.

Do this before any new driveway. Again, search for "How to do it.."

Do your neighbours have these problems?

2. Introduce say min. 3 new "standard" 10" x 6" air bricks. Dont allow the joist tails to block them.

3. There should be no ground contact with the external plinth or render.

4. The plate below the joists must be entirely removed - do it in sections.
It will be rotted out. Make good with cut brick.

5. Given that the bay brickwork is solid then you will have damp penetrating to the internal plaster and skirting!

6. The green corrosion on a copper pipe - what is this pipe supplying?

7. Paste the joist tails with a "mayonnaise" anti-fungal, and wrap and cap with DPC to about 6" or "8 back.
Thoroughly clean out all ex-timber pockets.

8. Now is a good time to extend wiring/outlets and any pipework.

9. Dont sweat the smell, it will clear up soon enough with good through ventilation. So make sure that air can freely travel from front to rear of the house.
10. While you are down there, why not check your rear elevation sub-area for timber/joist, and ventilation conditions.
And whats the condition in the hall sub area behind the porch?

11. Joist size quick calc is: Span in feet - divide by 2 - then add 2.
eg. a 10ft span - divide by 2 = 5 - add 2= 7".
You would require 2" x 7" joists for a 10ft span.

12. Dont go mass spraying any chemicals or buying special timber.
Except, perhaps, spray or paint a little cheap anti fungal chemical on the brickwork and wood thats close to the brickwork.

 

[skhudy]

I'm only a DIYer, but at a guess, the main problem you have is in the driveway there should be a slope from all directions into the drain, it doesn't look like there is (I may be wrong) Possibly the drain is blocked too - open it, put your hand in a black bin back and stick your hand down it clear out the crap if you can. Water has been for years (since the driveway was put in?) been collecting against the house and seeping into the brickwork.

My driveway ground level is a few inches from the DPC, what I've done when I put my drive in was leave a 6 inch channel all round the house and fill with shingles. It allows water to run into the ground and keep away from the house.

Getting the driveway / drainage sorted, or at least the flat area at the bottom should be high priority.

Inside it looks like you've pull the boards back to where there is a perpendicular timber (resting on some pillars?) the joists rest on. Hopefully the damaged joists don't extend back further. If it were me I'd chop the joists here and put new joists from there to the wall, sitting in joist hangers, or on dpc in the wall. 4x2 will be fine for a run of 1-1.5m, if unsure you can always put a few extra in.

You could put a bigger air brick as part of getting the driveway sorted. the smell i think will go away once all the rotting wood is gone. Your radiator needs to be taken off and skirting replaced, the plaster could all be blown too.

You could spray the wood, but unless you sort out the driveway it's a bit pointless long term. Leaving it open as long as possible to let it dry out is best imo

*and yes agree with previous poster - why are you ripping up your entire floor! doesn't look like T&G, you should be able to pull up the odd floorboard if you want to see the state of joists in other areas

 

[ree]

I stand corrected. They are square edge floor boards not T&G. This suggests to me that previous work has possibly been done to the flooring.
Unless square edge was a joinery practice in that district.

arh,

it just occurs to me that perhaps you would like to look at my and other replies to a Rotting Floor Joists question of last thursday?

 

[sss1978]

I realised I had a similar driveway blocked drain problem cleaning with said black bin bag worked for me! Must be years of sludge n crap I cleaned out

 

[gregers]

your render may well need cutting back a tad as it looks like it could be bridging any dpc that may well of been installed and a drip bead installed, updating the air bricks are a defo.
when i do this sort of work i always make sure that any timbers do not touch any of the outside walls,wrapping all joist ends with dpc.
most of the time if you scrape away some of your over site you will uncover the brick stepped footings? cut the middle 1 off to create a bigger base to work from and build up using thermolite blocks to the required height less the wallplate and joists and floor,oh and make sure you leave gaps in the new walls if needed for the airflow,clear all the crud off the oversite,spray a masonery wet/dry rot fluid over all timber allowing fallout over the oversite,dont forget to spray any/all floorboards.
personally i would never use chip board on a ground floor,if at all.HATE the stuff with a vengeance.

 

[notsodiy86]

Hi,
Just come across this thread I know it's old but I'd like to comment as I recently had the same problem.

• Our house was made in the '50s (suspended timber floors)
• We had a driveway put in 2004
• The driveway slopes towards the house
• The original builders built the drive right against the air bricks so was the Aco drains built right against the walls
• 16 years later of rain bashing the bricks and seeping through the air bricks we had a wet rot issue
• The front of the house had saggy floorboards. We ignored it a few years back but this year it got really bad to the point it was unsafe.
• Called in a local carpenter and he identified that the front of the house has completely rotten and the best thing is to replace the joists, floorboards and skirting.
• One option was to only replace the front half of the rooms but we decided to do the entire rooms as didn't want to go down the road in 5 years only to see the other side was starting to wear (would mean ripping up again)
• So we had new timber joists put in C24 grade Klin dried wood. Then on top was 18mm WBP plywood then MDF skirting all the way around.
• Then to rectify the water ingress we had the driveway modified.
• The Aco drain was moved 10cm away from the wall (letting the wall and air bricks breath)
• The 10cm gap was filled with pea shingle gravel to let any water that did pass the Aco drain to soak down into the soil instead of bashing the bricks again.
• But was told that now that the Aco has been moved back the rainwater will go where it supposed to go (the drain and not sit against your bricks)
• The cast iron airbricks that were damaged from years of rain were replaced with plastic ones (£1.79 from Tool station)

So now we have new solid floors in both the living room and dining rooms.
The timber floors are being ventilated and the water ingress has been defended.

Horrible experience and expensive one which I don't want to go through again.