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[markfree]

Went into the loft today (as you do) and noticed some of the boards (what you nail the slates to) were damp with mold growing on them.

No signs of any leaks - could this be due to condensation or is there a more serious underlying problem?

Any advice would be welcome especially from oofer  roofers 

[cruisetopoland]

Went into the loft today (as you do) and noticed some of the boards (what you nail the slates to) were damp with mold growing on them.

No signs of any leaks - could this be due to condensation or is there a more serious underlying problem?

Any advice would be welcome especially from oofer  roofers 

Likely to be a ventilation issue, made worse by the recent cold damp weather.

Check any vents around the edge of the loft aren't covered by insulation or birds nests etc.
Should be fairly easy to resolve if it is not a leak of any sort-bear in mind it has been very windy and this can drive rain in to odd places.

As its mouldy, assume it is long standing condensation from poor ventilation?

[Kevin Wood]

Yep, sounds to me like poor ventilation. Either check what's there is not blocked or add some vents around the eaves.

Kevin

[mantahatch]

How old is the property ? have you got a proper slate roof ? and do you have felt or not.
The general rule with old slate roofs was no felt, but slate roofs which have been re slated may have felt under the slates.
If you have no felt it is unlikely to be a ventilation issue. More likely it is going to be a cracked slate or similar.

[cruisetopoland]

Yep, sounds to me like poor ventilation. Either check what's there is not blocked or add some vents around the eaves.

Kevin

If heavily insulated, perhaps some eaves vents and a couple of vented ridge tiles?

[Marks DTM Calib]

You say boards......do you mean batterns?

Anything been doneto the loft e.g. boarded, insulated etc.

Any recent new soffets and facias?

[mantahatch]

Yep, sounds to me like poor ventilation. Either check what's there is not blocked or add some vents around the eaves.

Kevin

If heavily insulated, perhaps some eaves vents and a couple of vented ridge tiles?

A genuine slate roof with no felt has many gaps around the slates and is very draughty, and if built before about 1980 unlikely to have ventilated eaves in the first place. Yes adding a lot of insulation won't help matters but generally without felt the roof will be very well ventilated.

Is the damp/mold confined to one or two area's or all over the place. All over the place could well be a ventilation issue, but one or two confined areas would be cracked/broke/missing slates or hips/ridges or even flashings around any chimneys or vent pipes.

[cruisetopoland]

Yep, sounds to me like poor ventilation. Either check what's there is not blocked or add some vents around the eaves.

Kevin

If heavily insulated, perhaps some eaves vents and a couple of vented ridge tiles?

A genuine slate roof with no felt has many gaps around the slates and is very draughty, and if built before about 1980 unlikely to have ventilated eaves in the first place. Yes adding a lot of insulation won't help matters but generally without felt the roof will be very well ventilated.

Is the damp/mold confined to one or two area's or all over the place. All over the place could well be a ventilation issue, but one or two confined areas would be cracked/broke/missing slates or hips/ridges or even flashings around any chimneys or vent pipes.

Well put!  I renovate houses and have gfound wet usually is from a leak, mould from condensation.  Old slate roofs have 'natural' venting!!!

[Marks DTM Calib]

Hence the question about boards....as that does not stack up with a standard roof install (unless its shingles).

[mantahatch]

Yep, sounds to me like poor ventilation. Either check what's there is not blocked or add some vents around the eaves.

Kevin

If heavily insulated, perhaps some eaves vents and a couple of vented ridge tiles?

A genuine slate roof with no felt has many gaps around the slates and is very draughty, and if built before about 1980 unlikely to have ventilated eaves in the first place. Yes adding a lot of insulation won't help matters but generally without felt the roof will be very well ventilated.

Is the damp/mold confined to one or two area's or all over the place. All over the place could well be a ventilation issue, but one or two confined areas would be cracked/broke/missing slates or hips/ridges or even flashings around any chimneys or vent pipes.

Well put!  I renovate houses and have gfound wet usually is from a leak, mould from condensation.  Old slate roofs have 'natural' venting!!!

For my sins, when I left school I wet straight into an apprenticeship as a bricklayer, then spent many years on renovating and refurbishing old rental properties. That is until I said stuff it one day and then went and did something completly different, motor vehicle, and then said stuff that after 10 years and had a complete change again.  Finally I am generally happy now in my work.   

[mantahatch]

Hence the question about boards....as that does not stack up with a standard roof install (unless its shingles).

I assumed he meant battens, but as he is so far north of me, I wonder if they used a slightly different way of attaching the slates. I assume it may generally be a bit windier up there and maybe they use slighty wider battens and quad nail them rather than double nail.

Construction practice does vary quite a bit accross the country and I admit I have assumed quite a bit.  :-/

[markfree]

Thanks for all the replies 
The house was built around mid eighties so has roofing felt and concrete roofing tiles and not slates as I originally said.
There are 2 cold water header tanks in the loft - one for boiler and one for the hot water emersion.
When you are up in the loft it is virtually pitch black so I guess there is little ventilation and the loft insulation is stuffed right up to wall.
I'm now fairly sure it's a condensation problem so I'm going to put a de-humidifier up there to see if it cures the problem.
I was worried in case we had to sell the car to (literally) keep a roof over our heads
Thanks again guys

[mantahatch]

Thanks for all the replies 
The house was built around mid eighties so has roofing felt and concrete roofing tiles and not slates as I originally said.
There are 2 cold water header tanks in the loft - one for boiler and one for the hot water emersion.
When you are up in the loft it is virtually pitch black so I guess there is little ventilation and the loft insulation is stuffed right up to wall.
I'm now fairly sure it's a condensation problem so I'm going to put a de-humidifier up there to see if it cures the problem.
I was worried in case we had to sell the car to (literally) keep a roof over our heads
Thanks again guys

OK then there is a high probability it is a condensation problem. a dehumidifier will only dry it out for now, long term you shoud fit eaves vents and maybe a ridge vent or three to get some natural airflow going. And make sure the insulation does not cover the eave vents. 

I think it is pretty much what Kevin and cruisetopoland suggested in the first place.


Oh and I take it both water tanks have lids on and have insulated sides and lids.

And I don't no if the rules have changed but we allways left insulation out where the loft tanks where, I mean just a small square so that some heat would escape to the area under the tanks to prevent freezing.

[Kevin Wood]

The problem with using a dehumidifier in a place that has ANY ventilation and is not insulated from outside is that the device can only extract water at a limited rate (and has quite a high power consumption while doing so) so you may well find it fights a losing battle trying to keep a loft space dry.

By all means try it for an experiment but ventilation will be more effective and free.

Kevin

[redelitev6]

We are currently renovating some bungalows in Newcastle,these have had terrible condensation problems due to loft insulation covering the soffit vents, a house of your age might not even have any ventilation so check that you actually have any vetilation up there,if not it would pay you to install either some vented ridge tiles and some form of soffit vents to get some air flow into the loft space,also check the thickness of your loft insulation as it could be letting warm air into the loft ,which will cause condensation problems