Internal condensation

egorski

These posts were moved from here - sinnerboy



I'm following this discussion with great interest. I have a 1940's solid wall
house and have been living there for 2 years. We noticed severe condensation in the corner rooms of the house following the last two years.
These corner rooms ended up getting some fantastic mildew in them.
I dry walled on wall in each ofthe two worst rooms after the first cold winter (North and North East corner rooms) - with spectacular good results. However, I'm a DIY dry waller
with children so I don't get much time to finish off the more challenging walls in these rooms with radiators/vents/windows etc.....

So - I have been wrestling with the exterior wall rendering solution - however, I would have to say that it is seriously expensive and I agree with Heinblood that I'm not convinced its worth it. I do concede that with rising energy prices it may become more viable - I just cringe at the thought of spending 10k odd on insulating the outside of the house.

I recently discovered something called SEMPATAP and was wondering if
anybody had any experience with this - it would seem to be a good intermediate solution between EWI and dry walling.....


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BryanF

egorski wrote: »

I'm following this discussion with great interest. I have a 1940's solid wall
house and have been living there for 2 years. We noticed severe condensation in the corner rooms of the house following the last two years.
These corner rooms ended up getting some fantastic mildew in them.
I dry walled on wall in each ofthe two worst rooms after the first cold winter (North and North East corner rooms) - with spectacular good results. However, I'm a DIY dry waller
with children so I don't get much time to finish off the more challenging walls in these rooms with radiators/vents/windows etc.....

So - I have been wrestling with the exterior wall rendering solution - however, I would have to say that it is seriously expensive and I agree with Heinblood that I'm not convinced its worth it. I do concede that with rising energy prices it may become more viable - I just cringe at the thought of spending 10k odd on insulating the outside of the house.

I recently discovered something called SEMPATAP and was wondering if
anybody had any experience with this - it would seem to be a good intermediate solution between EWI and dry walling.....

condensation: what ventilation do you have?

by spectacular what do you mean? I worry in some situations, Drylining may have just covered up any condensation problems

Sempatap: I'm not familiar with this product, but I can't see a BBA cert on the website + I wonder if its only suitable to bring the U-value down marginally. just had a quick look an the net there, and found this report on it. http://ecovation.org.uk/htmldesigns/nineteenthcenturyterrace.html
it claims to be breathable and stops damp! I'd be keen to see some data to prove these claims..

see here re another forums comments http://peckhampower.org/forum/general-discussion/sempatap-diy-product-to-insulate-sold-walls

http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3295&page=1

Not convinced YET!

Personally I'd like to see people dryline with breathable, healthy materials, I've also been following this discussion closely, I appreciate the need to extensively insulated many of our homes, but I'm keen to see more natural (low embodied Carbon) products used.

I appreciate you want a simple/ cheap solution, and there's plenty of products claiming to be that. however, many of them are products developed for new construction and may not be suitable for existing buidlings, definitely not without careful consideration and professional advice.

Apologies for going of the EWI tread

egorski

The room is ventilated with a subfloor vent and also a old style vent at the top of the wall. Its about 4m square - one external wall has no features on it (no windows, radiators) etc - the other external wall has all the features.

I know the last two winters have been exceptionally cold and anecdotally, a lot of people have experienced condensation problems for the first time. However, ours was spectactular - the bottom 1m of the "featureless" wall was so wet we had pools of condensation forming on the floor. It was so bad that we actually thought a pipe had burst. I dry lined this wall with battens and 75mm thick "warmboard" - foam+moisture barrier+plasterboard. The difference has been amazing - The wall is warm to touch and not a drop of condensation. However, the wall with the features still has a condensation problem - but mainly in the corner and behind the curtains etc.

Anyhow - this is how I see it.
(1) EWI - very expensive - questionable payback etc
(2) Dry lining the remaining wall - time consuming and messy. I would need to take off the radiator and do a lot of work to get it looking correct. The wall is probably 30% window and 20% radiator and has plugs, light switches, panic alarm, curtains, window sill etc.
(3) Sempatap - I agree that this will never be as good as the other two but it may be a good solution for this problem. The major source of heat loss has been removed from the room - "the wall with no features".

If succesful, I may pursue this approach in other rooms - dry line the main "featureless" walls and sempatap the difficult ones.

Again - apologies for going off the main thread - but it does seem to a discussion on the virtues of EWI vs dry lining vs others....

Carlow52

Are happy that you don't have a rising damp issue here before you seal it all up?
If u have internal solid walls that tie into the external walls then they will become the problem due to cold bridging.

You need to look at the production of moisture in the house
bathrooms
kitchen
bedrooms

egorski

Hi Carlow - I was very careful to check that there was no rising damp.
I actually lifted the floorboards and checked underneath!

The only point I have had condensation on my new dry line wall is the ends
of two screws I used to bolt into a fitting on the cold external wall. The metal screw heads collect moisture and have started to rust!

The problem happens in all the corner rooms of the house - one of these
rooms doesn't have a bathroom anywhere near it and doesn't have any
occupant (no moisture).

Carlow52

egorski wrote: »

Hi Carlow - I was very careful to check that there was no rising damp.
I actually lifted the floorboards and checked underneath!

The only point I have had condensation on my new dry line wall is the ends
of two screws I used to bolt into a fitting on the cold external wall. The metal screw heads collect moisture and have started to rust!

The problem happens in all the corner rooms of the house - one of these
rooms doesn't have a bathroom anywhere near it and doesn't have any
occupant (no moisture).

Even in still air, moisture laden air will migrate around the house so as to equalise the differential vapour pressure caused by damper air versus drier air.

When u lifted the floor boards did u see a dpc?

Whats the subfloor finish

egorski

Okay - I've put some more thought into this - and I think I'm going to go for it.

Here is my thinking - I need to insulate the final wall in this room. The wall is about 30 to 40%. This is a PVC double glazed window. I looked up the U-value for this window and they are reported as 1.6.

I absolutely don't believe that Sempatap does a better job than dry lining or ewi for insulating - however - there is no point in me insulating the wall so that it has a lower U value than the window. Sempatap reduces a solid wall's U -value to 1.5.

Anybody see any flaws with this argument?

BryanF

egorski wrote: »

Okay - I've put some more thought into this - and I think I'm going to go for it.

Here is my thinking - I need to insulate the final wall in this room. The wall is about 30 to 40%. This is a PVC double glazed window. I looked up the U-value for this window and they are reported as 1.6.

I absolutely don't believe that Sempatap does a better job than dry lining or ewi for insulating - however - there is no point in me insulating the wall so that it has a lower U value than the window. Sempatap reduces a solid wall's U -value to 1.5.

Anybody see any flaws with this argument?

where too begin:)
So far, i think you have not adequately assessed the condensation issue, if I was you, I would consider inviting the best condensation/ dampness expert in the area and give him an hours work. he can at least strike of a few of the maybes

how do you know "The only point you have had condensation on dry line wall is the ends of two screws" is it possible the drylining has hidden the problem?

your assumptions regarding windows and walls
(these figure may be a bit off, but) its €1000 per msq to get glazing to circa a U-value of 1[FONT=Arial, Helvetica, sans-serif].0 W/(m2k) [/FONT]
but you can get a wall U-value to 0.15[FONT=Arial, Helvetica, sans-serif] W/(m2k)[/FONT] with EWI for €100 per msq. hence people put more insulation on the wall elements, which you also happen to have a lot more M2sq of. (i'm not advocating ewi, just dont like drylining)

I would suggest you take professional advice and if your not convinced ask if he/she can do / get a wall calculation to assess the interstitial condensation risks of dryling a wall that has such a condensation issue.

alternatively,

If you have your mind made up, would you put a temperature/ humidity data logger into the last wall you wish to dry-line (between the insulated board and painted wall surface).

Then over the next winter you will have a better idea of the resulting condensation cause before you dryline the rest of your house.

they cost €50, are smaller than a match box and data can download to an excell doc without removing. I'm sure there'd be many people in the arch tech forum interested in the results.

kind regards Bryan

icbarros

BryanF wrote: »

So far, i think you have not adequately assessed the condensation issue, if I was you, I would consider inviting the best condensation/ dampness expert in the area and give him an hours work. he can at least strike of a few of the maybes

+1

BryanF wrote: »

I would suggest you take professional advice and if your not convinced ask if he/she can do / get a wall calculation to assess the interstitial condensation risks of dryling a wall that has such a condensation issue.

+1

Condensation is a very serious and complex problem. You need to know exactly what is the cause of this before you decide what's the best type of intervention.

BryanF

Egorski,
Let us know what you decide, I'll supply the data loggers if you wish to go the dry-lining route

Al Katraz

Egorski, do you know where to buy Sempatap in Dublin?

egorski

Hi All,

A quick update. Its taken me a year to get around to putting the
Sempatap up. I have put it up in one room and left the other
practically identical room untouched, so I have a control to see
if the Sempatap works this Winter.

The glue has been stored outside for the last year and a half. It
said on the tin that it should not be stored below 5 degrees - so
I hope it hasn't been affected.

I have got as far as cutting the strips and putting it on the wall.
If you know how to wall paper - then its easy. The key
thing is to let it roll down the wall......

next job - filling the cracks.....

Roll on the Winter.....