Timber rot - what if you just can't remove the moisture source?

JustAnotherSaver

It will forever rot, that much is certain but what is the best you can do?

I'm talking about my floor joists. They're 6x2. I've no idea if they're original (1930s) or not. If they are then i'd say they're doing pretty good as the cause of the moisture is the stream that passes under our house so it'll have been damp under there from day 1. Well maybe not quite day 1, who knows.

The majority seem ok but some are damp where the ends meet brick work.
One in particular seems quite soft. I'd say about 10mm of the 2" is soft & i've no idea how much of the 6" is soft as i didn't want to probe the screwdriver too much. I doubt it'd go halfway but it was reasonably soft.

So as said - there's no way we can eradicate the moisture & i believe rot will set in at 20% content?

So what do you do?

Money most certainly IS an issue here as we're not made of it. Concrete beams was 1 suggestion but we need access to the subfloor as there's a sump pump & in the event this will need changing we need access. Still, i suspect the upheaval of the floor, ripping out the joists & replacing with concrete beams & then laying the floor back down will be way way beyond our budget. Sounds many £1000s expensive.

But still, if you can't remove the moisture factor, what CAN you do?
Make the best of a bad situation i know. And best may not always be good enough, but if it's all you can do then it's all you can do.

gmgmgm

Tricky problem indeed.

A thought- ventilation. Can you ventilate the area more? Has ventilation decreased in the last few years?

If this was a bathroom, you'd put a humidistat fan in asap. Obviously this isn't a bathroom, but this could be something to research.

JustAnotherSaver

No not a bathroom. We're talking about the subfloor crawlspace of my living room. The drop is approx 1mtr & i got down there yesterday to check out the air bricks.

The living room is 6.5mtr -x- 3.5 mtr & then there's a section which cuts off to the small hall.

There are 2 air bricks to the front of the living room & there is 1 to the side of the hall. These will be 9x6 air bricks square holed.

The first time i went down there the cavity wall insulation fluff-stuff had blocked the front air bricks which i cleared out.

I went down again as i said yesterday & crawled to the back which is a solid brick wall. Beyond this brick wall (above ground) is the diner which was built on a solid floor in 2000. There are 2 air bricks on the outside of the diner & they've channelled some sort of square plastic piping from these air bricks leading in to the subfloor of the living room. Rather than the full air brick allowing air to pass the square pipe is perhaps about 50mm-75mm (i didn't have a tape).

These were well blocked with that fluffy stuff. I have freed this up.

So to summarise:

2 air bricks at the front of living room
1 at side of hall
2 at rear of living room with a 50mm-75mm square pipe leading to the outside air bricks at the rear.


I'm far from an expert, but to my mind, i imagine you could make the ENTIRE lower wall (that leads to the subfloor) one huge continuous air brick so that it spans the whole length of the hall at the side, the front, right across the front of the living room (& then that'd be your max as nothing can be done with the other walls) and it would STILL not be enough ventilation. As i say, i might be wrong there & another couple may well bring the moisture content to an acceptable level. I just don't believe it. I would love to be told (proved) wrong though as it would solve my problem.




NOTE: I know i've posted various issues with this room over recent months. This isn't an overnight fix & we don't have an endless pot of cash unfortunately. This however is a new problem i've found, which is why it's in a new thread

Doozergirl

As many air bricks as is sensible, it won't hurt. Bear in mind, there has been NONE for quite some time, so everything is an improvement at this point. I'd go for two or three more.

Ventilation will almost certainly be the main culprit. You could put a new DPC under the joist level if the area is exposed on the outside, or indeed remove earth from outside to allow that, but ventilation may just be enough.

JustAnotherSaver

Doozergirl wrote: »

As many air bricks as is sensible, it won't hurt. Bear in mind, there has been NONE for quite some time, so everything is an improvement at this point. I'd go for two or three more.

Ventilation will almost certainly be the main culprit. You could put a new DPC under the joist level if the area is exposed on the outside, or indeed remove earth from outside to allow that, but ventilation may just be enough.

The majority of the joists seem fine, which is surprising given the amount of water down there causing the moist air.

There is a mini brick wall in the middle of the living room (underneath obviously) that the joists rest on top of. It is the one that is nearest the fireplace/hearth that is worst. The end is really quite soft. Thankfully not a massive piece but i know it can't get better than it is.



Regards air bricks - we need to get creative & come up with something to stop them from getting blocked. Eventually when we get round to carpeting, we'll have no access to the subfloor so we need a permanent solution.

I was wondering if you guys could suggest something?


The only thing i can think of is to build some sort of wooden frame perhaps that'd look like one of these [ rotated clockwise 90degrees. It should then, in my mind, stop the fluffy insulation dropping & blocking the air brick. I don't know if there's a better approach or something on the market that would be easier.

On the topic of air bricks - how simple/costly/risky is it to install them?

andyhop

Why not just drill core holes from out to in then sleeve with soil pipe and stick a meshed grille on external to vent and stop rodents . Something you could diy with a hire from the local tool shop

For existing vents I would suggest getting some tin sheet and just hammer and bend to suit over a bit of timber, will stop anything falling down and again easy to diy

woodbutcher_2

You'll probably find that the cause of the problem is the dpc which sits on top of the sleeper walls beneath your floors. Sleeper walls add support to the rafters and are usually built with air gaps in the brickwork.

The dpc will no doubt be slate, with a wall plate on top of it, on which your joists will be attached.

I've done a few of these over the years including my own house. The solution is to remove the lot. Flooring, joists, wallplates and start again with tanalised timber. Bed new 1"x4" wallplates on sand and cement with dpc beneath to the sleeper walls, making sure the levels are correct with existing floors. Next day, put on new tanalised joists and top off with moisture resistant chipboard. A big upheaval, but not that expensive materials wise and quite simple to do.

Make sure air bricks are clear in the future and problem should be solved.

JustAnotherSaver

andyhop wrote: »

Why not just drill core holes from out to in then sleeve with soil pipe and stick a meshed grille on external to vent and stop rodents . Something you could diy with a hire from the local tool shop

Thanks for the suggestion.

What would be the difference between that & just installing an air brick? Aside from depending on the length of pipe, it could be chanelled to draw the air in further under the floor - or is that why you're suggesting it?

I should add right now, i could most certainly not DIY this. I don't have the skills/confidence/knowledge on how to do this so i'd have to get someone.

I do wonder why the current air bricks don't seem to be ducted. They just seem to be bricks placed in the wall. Air ducts would surely stop the cavity from falling down, so i wonder why they haven't installed them.

For existing vents I would suggest getting some tin sheet and just hammer and bend to suit over a bit of timber, will stop anything falling down and again easy to diy

Thanks

andyhop

JustAnotherSaver wrote: »

Thanks for the suggestion.

What would be the difference between that & just installing an air brick? Aside from depending on the length of pipe, it could be chanelled to draw the air in further under the floor - or is that why you're suggesting it?

I should add right now, i could most certainly not DIY this. I don't have the skills/confidence/knowledge on how to do this so i'd have to get someone.

I do wonder why the current air bricks don't seem to be ducted. They just seem to be bricks placed in the wall. Air ducts would surely stop the cavity from falling down, so i wonder why they haven't installed them.

Thanks

Far easy to cut a core than chip out brickwork. A 125mm core on a average house can be cut in 10-15mins. A hour to line and fill with expanding foam and fit grille. Cutting out a brick, piecing in a air brick would take 3-4hrs

JustAnotherSaver

woodbutcher wrote: »

You'll probably find that the cause of the problem is the dpc which sits on top of the sleeper walls beneath your floors. Sleeper walls add support to the rafters and are usually built with air gaps in the brickwork.

I tell you what - you're good. There are indeed air gaps between the bricks. I wondered why this was tbh as the wall does not run the width. There is a bit of a wall to one side connecting to the chimney base, and a bit of a wall connecting to the wall opposite the chimney with an opening between for you to crawl through. Surely that's enough for good air flow.

The dpc will no doubt be slate, with a wall plate on top of it, on which your joists will be attached.

Indeed there is slate there. Not sure what you mean by wall plates though. From what i saw there were just joists, slate & the brick wall, nothing else. Oh, there is some sort of felt like material underneath the slate, so it'd go brick wall>felt like material>slate>joist>floorboard.

I've done a few of these over the years including my own house. The solution is to remove the lot. Flooring, joists, wallplates and start again with tanalised timber. Bed new 1"x4" wallplates on sand and cement with dpc beneath to the sleeper walls, making sure the levels are correct with existing floors. Next day, put on new tanalised joists and top off with moisture resistant chipboard.

I appreciate what you're saying & deep down i guess i know you're right - it needs coming out.

Problem is we simply don't have the money.

As i say, i've no idea how old these joists are. I suspect original 1930, so they've done well to last so long in these conditions. We don't have the cash to be ripping up the floor & doing such major work. It's not that i'm ignoring what you're saying because i'm not, but we're just not in a position to renew it right now. I think we will have to just be mindful of it & see how we get on. It'll go over time i suspect (even though it's had 80 years in these conditions) but for now we're just not able to do anything on that scale, so we need to do the best we can do right now.
Not wanting to cause offence as i have taken what you've said on board.

A big upheaval, but not that expensive materials wise and quite simple to do.

Perhaps not expensive in terms of material, but it's not something we could do. We'd need to get a professional in to do the lot from start to finish. I suspect we could be looking at a reasonable amount here & that's on top of the £1000s we'll have to spend getting the damp walls seen to.

Make sure air bricks are clear in the future and problem should be solved.

I wondered - the moisture content in sections is about 30% with a damp meter. I guess this is one of those unanswerable questions but i'll ask anyway -

how much would you expect the current (working) air bricks to bring this down by & how much would additional air bricks help? I'm not looking for anyone to say "from 30% to 19.879%" but should it make a big difference?

I also asked earlier about how many to install. I took a look today & there's actually 2 in front of the big window, 1 in front of the living room, 1 at the side.
I don't know how much gap you need to leave between air bricks but there's scope for certainly 1 between the 2 already there, maybe 2. Maybe another at the side & that may be it. POSSIBLY another down the side of the house but i wonder how much air will be channelled there anyway.



EDIT: I'll go ahead & ask as we seem to be making a habit of getting the wrong tradesmen for jobs. Is this a specialist area (so we'd need to get in some job title i've never heard of before) or would your regular 'decent' builder be fine for this?

woodbutcher_2

The air bricks are not your problem. You can add as many as you like and it won't make any difference. The ones that were fitted originally will do the job if they are clear and you have a throughdraft.

The problem is water soaking up your sleeper walls, through the old and broken down dpc and soaking into the timbers, therefore rotting them. My house is the same age and the floor was at the end of it's lifespan. It cost me a couple of hundred quid for timber, sand and cement and a couple of days upheaval. I didn't have to pay labour charges admittedly, but it shouldn't be a massive amount to sort out and sounds like it needs doing.