# Damp walls issue



## BMac (4 Jan 2010)

Got a problem. I noticed damp in a corner of my bedroom. When I moved wardrobes etc I discovered a triangle of damp from near the ceiling to the floor in one corner and it extends about 15' along the (external) wall to a height of about 3'.

Background - old cottage style bungalow built 1922, solid walls, damp-proofed 16 years ago when I moved in. I got all the solid walls at the front half of the house treated with damp-proof course (injection) and there is no damp anywhere else.

At the minute the damp is visible and the paint and plaster is 'foaming' and falling off in places.

I am gutted but that won't fix anything. Is is worth getting a dehumidifier to dry the room out before calling a builder, who will probably find thousands of pounds worth of work to do, just in case it's an air circulation problem? The damp is only behind units that were along the exterior wall.

Any advice, thoughts or suggestions will be greatly appreciated.

Brendan


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## Oryxdesign (4 Jan 2010)

Have you checked that you don't have a leaky gutter?


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## BMac (4 Jan 2010)

This is quite a coincidence. About 3 minutes ago I was outside looking for any damage that might have occurred and I wondered if the gutters were full because I haven't cleaned them for two years due to health issues and never got around to getting someone else to do them. Tomorrow I'll get up and have a look.

Thank you.

Brendan


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## MikeG. (4 Jan 2010)

Difficult to comment without a site visit, I'm afraid....so general terms only.

Firstly, if the damp-patch is behind a cupboard it could simply be that you have a cold, uninsulated wall which attracts a bit of condensation and, because of the cupboard, there is no ventilation. Ventilation is a key to avoiding damp problems. Condensation is so often the cause of damp problems, and the answers are insulation and ventilation.

Secondly, check for all possible sources of damp.......leaking gutters and downpipes, ground built-up too high outside, leaking pipes/ cistern overflow pipes etc. Are there any external cracks that might allow the ingress of water? Does your pointing need sorting?

Don't go for a dehumidifier, because it will remove the best clues you have to the problem. You want to solve the damp problem, not, mask it. Is there good ventilation to the room? Keep the furniture away from the area for a while, to see if ventilation solves the problem.

Don't get a stranger to look at this, unless there is no-one (architect, surveyor etc) that you know. They will simply see pound-signs.

Mike


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## BMac (4 Jan 2010)

Thanks Mike,

I am fairly confident that there are no leaks but the gutters could be a big factor because I have lots of Ash trees close to that side of the house and the gutters do get a lot of leaves.

I'll pass on the dehumidifier, that makes a lot of sense. 

Ventilation is a issue because the rooms are small and we joined the front room to the back room (of the original house) to get a bedroom and connected dressing room. So there is only a door, 3' archway connecting the rooms and two top windows at the front. There's another medium sized window in the room we sleep in. We keep the windows and door open at night and try to keep the ventilation up but there are areas where through-flow of air is poor. I saw a system that is fitted in the attic and blows air back down to increase pressure inside the house and supposedly repel damp and improve air movement. I have no idea if it is any good.

Getting an expert - one of my mates is a plastering contractor so I'll get him out. He's very good.

Thanks again,

Brendan


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## MikeG. (5 Jan 2010)

Brendan,

the air-handling unit you speak of is called a whole house ventilation system, and because it recovers waste heat and feeds it back into the house, you will find google deals with it as MVHR (mechanical ventilation with heat recovery).

They are brilliant, brilliant bits of kit. If you live in a bungalow then I would say do it straight away. Retro-fitting in a bungalow is really easy. It is more problematic in a 2 storey house because you need to get a 4" pipe to every room in the house, and dropping 2 or 3 vertical legs through the first floor rooms is never straight-forward.

This http://www.vent-axia.com/range/air-minder-plus-ultimate-heat-recovery-unit.html is the latest version of a unit that I have fitted in or specified in countless houses, and this http://www.vent-axia.com/range/sentinel-kinetic.html is the one I plan to fit in the next house I do. In a reasonably insulated house with double glazing, they will reduce the excess moisture in the air to a level that you will very rarely see any condensation at all. Even in the bathroom, they'll clear the steam from a shower so quickly that you can shave without wiping the mirror within a couple of minutes of getting out of the shower. If you are so minded, you can watch the condensate run out of the condensate drain within a few minutes of finishing the shower or bath.

Depending on your pipe runs, and if you do it yourself (its a simple job), you should be able to do a house for £1200 to £1500........but don't quote me!!! I would never do a house without putting one in.

Mike


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## RogerS (5 Jan 2010)

Jeepers...have you seen the price :shock:


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## BMac (5 Jan 2010)

Mike,

This house is well insulated. I had the cavities done in the new section and the loft insulated during the first renovation to make the house habitable (new windows, doors, damp proofing, central heating etc). Since then I did an extension and put a new roof on the entire building. When I became medically retired I qualified for disability benefits which meant I got my house assessed and the only thing that I needed was upgraded loft insulation. That was a brilliant job, really deep and effective. So, this system you recommend is, in my opinion, well worth doing to sort out the ventilation problems in the old part of this house.

Again, many thanks,

Brendan


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## Daven (5 Jan 2010)

I am just in the process of fitting heat recovery ventilation system in our bungalow (thanks for the advice Mike). Double Glazing and floor coverings certainly have made the house damper!

The units are expensive, Screwfix do a Vent-Axia for £650 link

Not as affective as the top end but I am hoping it will still work for my requirements (2 rooms extract and 2 supply).

All I have left to do is the ducting and fitting the valves and we will be up and running! 

Dave


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## MikeG. (5 Jan 2010)

Dave,

that is older generation, and therefore a bit less efficient, but will do a grand job for you. I have also fitted that exact same unit, some 14 or 15 years ago and it is still going strong. Brendan, that one may well be worth considering. As an architect I just specify things on performance, so hardly ever look at the price........and £500 worth of saving is not to be sniffed at.

Mike


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## Daven (5 Jan 2010)

Thanks Mike,

Was a difficult decision, but being made redundant a few months ago I have to be careful now, plus planing to move at some point I felt that the loss of heat saving (say 15-20%) between the newer units and this one was better than doing nothing!

The cost of the ducting and valves is surprising as well - looking at about £300-£400 - hopefully I will do it for around £1000, not bad when I have seen quotes for silly money!!

Brendan - As you sound in the same situation as us, I hope to get this running over the next week or two, so can let you know how it goes! 

Dave


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## BMac (6 Jan 2010)

That's super Dave, I won't be doing this for a while until I get my mate to assess the situation and do any remedial work but I am definitely doing it. 

Mike, I almost remember the name of the system I originally saw, it was a 'Positive Air something' that had one pump increasing pressure inside the house. Your system is what I'm going for, especially when it has that 'summer mode' because the front of this house is like a storage heater and gets really uncomfortable in summer.

Thanks guys,

Brendan


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## RogerS (6 Jan 2010)

Curious about the ongoing 'maintenance' required for these ventaxia type units. Presumably they have a condenser and that it operates in a similar fashion to the condenser in a tumble dryer? if so then how often and how easy is it to clean the condenser as is needed regularly with a dryer. 

Or is that down to fluff in the dryer and so no filter needed for the ventaxia?


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## MikeG. (6 Jan 2010)

Roger,

no, there is no condenser. They are simply a fan in a box, with a plastic (usually) matrix heat-exchanger. This is simply layer upon layer of specially shaped plastic leaves, which allows the warm air to give up its heat to the cold air without actually coming into direct contact with it. The naturally occuring condensation drains to the bottom and runs out down a pipe. Couldn't be more simple.

Maintenance is no more than an occasional wipe out of the box, and flush through of the heat exchanger (in the bath or shower). I've done mine 2 or 3 times in 10 years.

Mike


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## RogerS (6 Jan 2010)

That is elegant. I like that.


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## dickm (6 Jan 2010)

I'd echo what Mike says. We have a full MVHR system, and it just sits there in the loft happily ventilating the bungalow without any attention apart from an annual-ish cleaning of the filter. Mind you, it's been installed since 1999-2000, so may well be coming to an age where it needs attention  

With outside temp of around -5C, we are using about 4kW to keep the whole house warm. Possibly having a foot of snow as insulation on the roof helps! But at least the snow stays there, unlike most of the local houses where it melts off as soon as they put their heating on.


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## Mark Hancock (7 Jan 2010)

The timing of this thread is unbelieveable. I've just encountered the same problem as Brendon and was at a loss what to do.

Is there any way I can save/flag this thread for future reference?


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## BMac (7 Jan 2010)

Mark,

There's an option, bottom left of the page 'Watch This Topic For Replies'. I selected that to keep it alive for me.

Brendan


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## Mark Hancock (7 Jan 2010)

BMac":22ev064q said:


> Mark,
> 
> There's an option, bottom left of the page 'Watch This Topic For Replies'. I selected that to keep it alive for me.
> 
> Brendan



Thanks Brendan - sorry for spelling before  

I've done that. I'm just thinking a bit further ahead whe I can get round to sorting the problem. Maybe I'll just print it off for now.


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## Daven (7 Jan 2010)

I will take some pictures soon and post them here if it helps - just not been able to do much this week!  

Dave


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## BMac (7 Jan 2010)

Yes please Dave.

Mark, no probs about spelling, wish that was the worst I've been called.


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## Daven (14 Jan 2010)

Sorry not had much of a chance to get in the loft but here are the pictures so far!

This is the unit - Vent Axia LoWatt HR204






The heat exchanger





The Insides





More to come :wink: 

Dave


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## RogerS (14 Jan 2010)

Mark Hancock":iry9mndj said:


> The timing of this thread is unbelieveable. I've just encountered the same problem as Brendon and was at a loss what to do.
> 
> Is there any way I can save/flag this thread for future reference?



or simply bookmark the page in your browser.


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## Daven (19 Jan 2010)

Well I have got most of the ducting in place and and wrapped with insulation. Used the router to cut the holes for the vents in each room just have the external vents to fit now.

Question for Mike if he is reading - I want to fit the vents in the soffits as this is the easiest for me, how far apart should they be? The manual say 2 mtrs but the shop I bought the ducting from said that was excessive.

Regards

Dave


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## MikeG. (19 Jan 2010)

Well, as far apart as you can Dave........but a min of 1200 I reckon. Try and make the terminals accessible, because you will want to clean them occasionally.....and make sure there is an insect mech on the "in" terminal......it sucks loads of insects in otherwise.

Mike


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## Daven (19 Jan 2010)

Thanks Mike.

Terminals are easily reached and at the front of the house so it will remind me to clean them LOL.

I also need to find a route for the condensation pipe - and then almost ready to switch on and balance!

Thanks for you help

Dave


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## Mark Hancock (19 Jan 2010)

RogerS":2f4fixj2 said:


> Mark Hancock":2f4fixj2 said:
> 
> 
> > The timing of this thread is unbelieveable. I've just encountered the same problem as Brendon and was at a loss what to do.
> ...



Should have thought of that!  Thanks Roger.


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## Daven (23 Jan 2010)

Well managed to get it up and running yesterday - have got a roof vent tile, but need to get it fitted so exhaust is via an existing roof vent for the time being.

amazed to see how much condensation that has come out already - hygrometer is saying around 51% two days ago it was around 60%!

All in all I have spent about £1k - www.I-sells.co.uk were excellent in supplying the ducting (albeit I collected from them). All ducting wrapped with Thermawrap insulation from Screwfix.

Noise is not too bad, bit like a small fridge for comparison, and we could only really hear it at night but have just put some carpet behind the fixings to try and make it less noisy.

So far I am glad we have done this - be interesting to see how it fairs long term!

Dave


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## MikeG. (23 Jan 2010)

Dave,

I should have said about the noise. Locate the unit above a hall or bathroom, not a bedroom, and make the first metre of the pipe runs (where they connect to the unit) in flexible insulated ducting. Sit the whole thing loose on a thick foam rubber mat, and you can chuck a blanket of insulation over the whole thing. 

You shouldn't really hear anything at night....have you tried running it at a lower speed setting?

As for the condensate drain......have a steaming hot shower, then go and watch the condensation run out of the building through the drain! You've just done the best thing you possibly could for the internal environment of your house.

Mike


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## BMac (23 Jan 2010)

Dave,

Thanks for the running commentary, I've been reading with great interest. My silence is not an indication that I've stuck my head in the sand and hoped the damp would go away but, rather, that I am investigating the installation and getting information on firms that do it here. I am unable, for health reasons, to climb about attics so I'm going to have to pay to get it done which is very frustrating because a few years ago I would have relished a job like this. Anyway, I will be posting on my progress when I have more background work done.

Your installation and Mike's advice have given me great confidence in this project.

Thank you both,

Brendan


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## Daven (23 Jan 2010)

Hi Mike,

No problem - I did know about siting the unit, unfortunately I did not have much of a choice regarding location. Living room is new build extention with flat roof and bathroom in middle of property so the unit is over the passage.

To be honest it is quiet and did not disturb us too much, in fact it is quite soothing (got a bit of tinnitus!)  

I have the unit on the slowest speed setting and I think the carpet behind the fixing has done the trick - we will see what it is like better tonight. I did in fact use flexible duct to connect the unit so that was lucky.

Thanks for you help and reassurance Mike, much appreciated.

Dave


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## Daven (23 Jan 2010)

BMac":2tnovdct said:


> Dave,
> 
> Thanks for the running commentary, I've been reading with great interest. My silence is not an indication that I've stuck my head in the sand and hoped the damp would go away but, rather, that I am investigating the installation and getting information on firms that do it here. I am unable, for health reasons, to climb about attics so I'm going to have to pay to get it done which is very frustrating because a few years ago I would have relished a job like this. Anyway, I will be posting on my progress when I have more background work done.
> 
> ...



Hi Brendan, no worries - I didn't want to hijack your thread but thought it would be best as more of a reply the the OP, so glad it is useful to you!

Regards

Dave


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