Ill explain from the begining, since buying a house it came with a detached single concrete prefab garage with a metal roof.All was fine till the weather turned cold and the metal roof frosted over inside then when it thored it dripped all over my car.

My first attempt at curing this was to fit a tube heat on a thermostat that came on at 6 degrees and went off at 6.1 degrees.

Come the next cold night it did the same again so i bought a load of kingspan and fitted that to the roof but that didnt work either

Will a wood and felt roof cure this problem and im lossing sleep over my car getting wet???

 

Have you got any air vents in the garage Ad? Circulating air should help.

 

a bit of ventilation should help, and maybe a dehumidifier to help get the moisture out

 

if you can lift the metal off the roof and place builders or roofers felt between the metal roof and the timbers and you will never have a drop of water again,

 

Tryed leaving the door open m8 and that didnt help

I have been looking at dehumidifiers and i will be getting one but i want to cue it without electrical equipment first

Would that not cause the roof to rust if i trap the water inbetween the felt?

 

That is the proper solution......

 

It's surely galvanise roof sheets?, if so it won't rust, if it's not then when you have the roof up paint the underside with some proper anti rust type paint like you would your front gate, there's not going to be that much water and it will sit and soak into the felt but will not leak thru, I've seen puddles in litres and gallons sit on top of felt in the case where the roof was leaking and it never leaked through the felt membrane

Having read your last post again I'd be more worried about the upper side rusting due to rain fallin on it rather than condensation on the underside , surely it's treated and galvanised?

 

What I did with a steel roof garage was put a wooden ceiling on bottom of trusses with some wall insulation on top of it but not touching the steel. Also a bit of ventilation between the space. Never had any issues in almost twenty years.

 

Or plenty of wood shavings between the two lol, plenty of soakage

 

I have thought of that but all the water will just drip on the insulation. Had sombody out today to measure up for a complete new wood/felt roof

 

Why replace a perfect roof man?

Lift the roof an put the felt underneath, it's a few quid a roll and it's what all new roofs are done with and what I did mine with recently and not a drip, so dry when I brush the floor the new concrete floor is still powdery

 

I had the same problem. You need to get the air moving I got a cheap 12v extractor fan from machine Mart and a frost protector. That did the job for me. Cost about Ł30

 

The condensation is caused by warm air hitting the cold sheets so insulation and ventilation between insulation and roof will stop it so nothing to drop on the insulation, I have two garages done same way and have never had any issues,

 

Dont work i have that on mine so its new roof time

 

If you have builders felt letting through water I guarantee it aint just condensation, it's a water leak u have mate

 

its builders felt and its soaking thru in some patches and when it freezes i have frost on the inside
going to do a flat roof with epmd sheeting next time

 

A little update here. My new dehumidifier arived from 4air this morning so i went straight to the garage and plugged it in.

I left it for 10-15 mins and there a nice little puddle of water in the tank



And in its new home

 

Any joy with the dehumidifier? Only other thing i'd say is warm up the moist air to(warm air holds moisture better). Also, as a previous reply, make sure nothing is soaking through the roof.

A similar post is here https://passionford.com/forum/genera...er-winter.html - i think you posted in to??

 

The kingspan will do sweet FA if there is no air gap between the roof and the kingspan. If the eves are open (vented) run a breather felt on the underside of the tin and so it runs off the external side of the eves then put the kingspan back up. Leave 25mm between the tin and breather felt and the felt and kingspan. This may be impossible without taking the roof off, but with out seeing it, it hard to tell. You may be able to pin it to the underside of the rafters?

 

I had a similar problem with mine getting condensation and dripping all over the electrics, so, i managed to get hold of some secondhand polycarbonate sheets (the stuff for conservatory roofs) and screwed that to the underside of the roof joists and sealed all the gaps from the inside, that way the heat was contained inside thegarage rather than going up to the joists and metal roof, i also made sure the were plenty of vents above the polycarb layer to allow airflow below the metal roof, havent had a drip since.
I keep checking the polycarb and so far no signs of any drips on it yet after several years