Moisture problems

[mansea]

Hi all, I have a few probs at the minute. The roof felt in the loft is suffering from masses of condensation, the trusses are moist and the water is dripping off the felt, this is causing damp on the insulation and ceilings beneath. I believe the felt to be non breathable bitumen type.

I have attempted to rectify the problem by adding lap vents for air movement in between the felt, I can't see any other form of ventilation, no visible tile vents, sofit vents etc.

One of the probs is I can't feel any air coming in from any of the lap vents, I don't know if the felt overlap is too much or if for some other reason there is lack of air movement under the roof tiles?

I have also noticed that near the ridge the felt overlap was done the wrong way by some utter idiot, so that if water were to get under the ridge and top 1 or 2 rows of tiles and get onto the felt below, when its running down the roof it will come straight through the felt. Is this at all rectifiable from inside the loft by manipulating the overlap correctly?

There is also a cold water tank in the loft and there is no lid, so I'm wondering if that is contributing to moistness and condensation? The insulation seems fairly consistent and the loft hatch is secure and insulated and theres no bathroom vent to worry about bringing warm moist air into the cold loft space.

Any thoughts on how to resolve please? TIA

 

[Harry Bloomfield]

Get a lid on that water tank quickly!

 

[catlad]

How old is the property?

 

[mansea]

About 1960s/70s

 

[^woody^]

How much insulation is above the ceiling?
Most of that condensation is from warm air from the rooms below

Is it a tank (sealed), or a cistern (no lid)?
Fit a lid to any cistern.

 

[JP_]

I had to put in about 40 felt vent things to get rid of condensation problems in my loft - which was new extension, and had a leaking extractor duct (now fixed).
My old 1930s loft (a bungalow of two halves) has no felt, and is always breezy and dry. And very dusty. But dry!

 

[mansea]

How much insulation is above the ceiling?
Most of that condensation is from warm air from the rooms below

Is it a tank (sealed), or a cistern (no lid)?
Fit a lid to any cistern.

Insulation is about 20-30cm, with no vapour barrier underneath.

It's a header tank with ballcock and no lid. I cant see in as its been fitted so close to the roof, about 1-2 inches, presumably access was too difficult to fit a lid, I suppose I could slide some tarp over the top and duck tape to create a seal? I've turned the valve off though, so there shouldn't be much water in there. I believe it only fills the immersion heater tank for the hot water system which I don't use. Theres no water coming out the hot taps which is fine as I don't use them. To be honest I'd be happy to decommission and rip the tank out, even more so if thats the suspected cause.

 

[Why Not Indeed]

Covering the tank with something impermeable should answer that question fairly quickly and is just about the simplest thing you could try doing.

 

[Harry Bloomfield]

Covering the tank with something impermeable should answer that question fairly quickly and is just about the simplest thing you could try doing.

A heavy piece of board, put on top of a sheet of plastic.

 

[JP_]

Covering the tank with something impermeable should answer that question fairly quickly and is just about the simplest thing you could try doing.

super quick solution would probably be a few strips of clingfilm over it?

 

[mansea]

Thanks all will defo cover the tank and see if the condensation improves, I took a pic on my phone and think its only about 6 inches of water in there but difficult to gauge, certainly wouldn't hurt to rule it out though. Whats the best way to empty it completely? Is there a drain plug or valve on these plastic loft tanks to drain the water completely? Or is it a case of sponge and bucket?

 

[Harry Bloomfield]

Whats the best way to empty it completely? Is there a drain plug or valve on these plastic loft tanks to drain the water completely? Or is it a case of sponge and bucket?

6" or 18" evaporation from it will be around the same. If you stop it filling and turn a hot tap on, it should be able to empty it completely. You can stop it filling by turning a valve of if there is one, or by tying up the float valve - piece of wood across the top and some string pulling the arm up.

 

[mansea]

Thanks, yes I've turned the valve off and theres no water coming out the hot water taps, but theres still an amount of water in the header tank. I'll seal it up in a bit and see if the condensation improves.

Could the header tank also serve to increase water pressure for the cold taps? Or would it purely feed the hot water cylinder? I guess the piping would give it away? If 3 pipes its just serving hot water and overflow? And I guess 5 pipes if its serving cold water supply also?

 

[Harry Bloomfield]

Could the header tank also serve to increase water pressure for the cold taps? Or would it purely feed the hot water cylinder? I guess the piping would give it away? If 3 pipes its just serving hot water and overflow? And I guess 5 pipes if its serving cold water supply also?

That varies by where you are in the country, you would have to go around turning cold taps on and flushing toilets to be sure.

 

[mansea]

The cold taps (and flushes) are still working with the one valve closed, I don't know if there might be a second valve hidden in insulation? Its by no means a traditional setup and a lot of what's been done is questionable and unconventional, so nothing would surprise me.