Loft condensation / ventilation

T

Timmyk86

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Hi all

First post here! Hoping you can help sort my loft space out. I have read several threads already including CONDENSATION IN LOFT (ANSWERS) - none quite answer my questions!

I have a Victorian semi-detached house with a slate roof and impermeable plastic undersarking. There's no obvious ventilation in loft space. One side is a brick gable end with the chimney breasts. There are no soffits and there doesn't appear to be any eave vents either.

I don't think there is enough ventilation up there, and there is a fair amount of white mould on the wood. The condensation was terrible when it was there (this coincided with having a very full house over Christmas).

The reason I noticed the condensation was because I wanted to (and since have done) fit a Nuaire Drimaster to sort condensation and poor ventilation in the house. Before installing it, I found lots of unexpected condensation on the undersarking. To address this I fitted 10 x Lap vents but in doing so noticed that the overlaps in the undersarking are quite large and not all the vents separate the entire overlap - so they probably aren't as effective as I want them to be.
Since doing that though, the loft does seem to have dried out but I'm still concerned there isn't enough air flow up there especially with the Drimaster in place.

I'd be grateful for some opinions on the best way to ventilate it. I'll probably have it converted in the not too distant future so will need to take that into account!

Options I've found:
1) Fit vent tiles
2) Fit an air brick in the gable end (there is a loose brick already between the chimney breasts, about halfway up the gable end)
3) Fit ridge vents

As mentioned, if any of them would also work with the future loft conversion, that would be great.

Any opinions much appreciated

T
 
Start with whichever you find easiest. You need ventilation on at least two sides so there is airflow.

Have you got any holes in the ceilings?

Are there tanks or pipes in the loft?

When you convert it, add permanent vents at the gable and the roof slopes.
 
Thanks for the quick reply.

There are holes for three ceiling lights, no massive gaps around the roses though.
There are a couple of old central heating pipes up there which do get warm - but they are covered by insulation. No tanks.

In terms of easiest first - what can I do myself? I could probably knock out the single brick and put in an air brick, but that is quite low in the gable end and probably wouldn't be compatible with a loft conversion and would only be one side.
I could also add more lap vents if you think that would help.

What do you think?

Thanks again
 
it will be hard to mortar in an airbrick without climbing up the outside

I suppose you could use a core drill from inside. There are a few vents than can be pushed through. Slope it down so any rain runs out. A hole at one end will not give a throughflow of air.

can you photograph the eaves (with the insulation pulled back)?
 
That's true. I couldn't just wedge a plastic one in there?
Photos of loft attached - would be really grateful to hear what you think.

Thanks
T
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Also pictures from outside the house to get an idea of what the eaves/roof looks
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like...
 
foxhole said:
Nothing you do now will affect a loft conversion .
Click to expand...

That’s good to know. Thanks. Does that suggest the whole roof will need re-doing if I get it converted?

That in mind- I’m still looking for the easiest way to ventilate that space!
 
Nice brickwork, good windows.

I'm a bit surprised there is no visible gap at the eaves. Must be a different style of construction from what I'm used to. I'm sure you could bore some big ventilation holes, but someone more familiar with your roof will know better.

Some of those timbers look to me as if they have been badly wet. Prod them with a flat screwdriver to check that they are sound (not with a round or pointed prodder as the marks will look like wormholes)

Taking out that loose brick would help, but you need to prevent rain or wildlife getting in. A plastic airbrick may fit.
 
JohnD said:
Nice brickwork, good windows.

I'm a bit surprised there is no visible gap at the eaves. Must be a different style of construction from what I'm used to. I'm sure you could bore some big ventilation holes, but someone more familiar with your roof will know better.

Some of those timbers look to me as if they have been badly wet. Prod them with a flat screwdriver to check that they are sound (not with a round or pointed prodder as the marks will look like wormholes)

Taking out that loose brick would help, but you need to prevent rain or wildlife getting in. A plastic airbrick may fit.
Click to expand...

Thanks, that's kind of you to say. The previous owners did a good job with the place (mostly!)

Worrying that you mention about the wood looking very wet. I'll get up there and poke it. Just looking to see if it's soft, right?

Regarding the air brick- I don't think that one (visible in the photo of the gable) is loose as such, but it does seem to be a single brick only between inside and outside. Hopefully if I make a neat enough hole, I can just push a plastic brick in from inside to out. Probably not best practice but what can I do.

Ventilating the eaves seems like the best thing though, as that would have to happen with a loft conversion as well. Any idea how to do that? Or what to put in the hole to make sure it doesn't leak?

Thanks again.
T
 
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airbricks most often go under the floor where a bit of rain penetration won't do much harm, but in older properties they are often laid on a piece of slate, which is waterproof, preventing the immediate bricks getting saturated. You could line the "bed" of your hole with some waterproof material,slightly tilted to encourage water to run outwards.

I haven't seen plastic duct in that exact size, but it might exist.

As for drilling the roof timbers, if no-one notices your thread here, you could ask on the Roofing section.
 
JohnD said:
airbricks most often go under the floor where a bit of rain penetration won't do much harm, but in older properties they are often laid on a piece of slate, which is waterproof, preventing the immediate bricks getting saturated. You could line the "bed" of your hole with some waterproof material,slightly tilted to encourage water to run outwards.

I haven't seen plastic duct in that exact size, but it might exist.

As for drilling the roof timbers, if no-one notices your thread here, you could ask on the Roofing section.
Click to expand...

Okay great, thanks.

I think as a starting point I'll add a few more LapVents (to make 20 total) and some EasyVents along the ridge (there's a lap in the plastic undersarking right next to the apex of the roof). That should hopefully provide some good in- and outflow of air.

I know not a permanent fix but I think that might come with a loft conversion. In any case, I'll ask in the roofing forum about drilling vents in the fascia board. Or did you mean about the timbers having been wet?

Thanks
T
 
I meant about how to ventilate through the eaves. But you will probably soon also know if they have been affected by water.
 
An air brick will inly be any use if it is high enough to ventilate the new roof space after conversion. That sort of eaves (fascia on corbel and dentil brick feature) would require over fascia type vents.
 
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