Condensation Issues in Roof

ps124

Hi all,

My roof seems to have a serious amount of condensation building up in it. It's a relatively new roof that was put in about 10 years ago.

My father (who is no DIY expert) says its due to me using the heating more during winter months which is rising into the roof. He thinks a dehumidifier will do the trick.

Will this work or should I get this looked into as a more serious issue?

Please help.

daveyjp

There is probably not enough airflow in the roof void. If you have loft insulation ensure it has not been fitted right to the edge of the roof as it will cover the soffits and prevent airflow.

Furts

daveyjp wrote: »

There is probably not enough airflow in the roof void. If you have loft insulation ensure it has not been fitted right to the edge of the roof as it will cover the soffits and prevent airflow.

This is correct but you might have over eaves vents, with breathable felt and a ridge ventilation. This should not give rise to condensation unless it is faulty. It is common at the era your house was built.

Is your loft access thoroughly sealeed and draft proofed?

Horizon81

As above, ensure any ventilation in the loft is unobstructed. Assuming all is fine there then yes you want to reduce the amount of warm moist air getting up there. A dehumidifier would indeed help, as would using extractors when cooking and bathing, and using a tumble drier rather than just letting clothes dry over radiators. Of course, thats assuming you have one.

Do you have any water tanks in the loft or any gaps where hot moist air could be getting up e.g. spotlights in the ceilings?

ps124

Hi,

Thanks for the replies. Yes I do have ceiling spotlights in all the rooms. We also do use extractors when cooking and bathing (also leave windows open). I wasn't aware that drying clothes over the radiator can cause condensation?

There are no water tanks up there and i'm not really sure whether there is a void or what ventilation is up there. I'll go up there and check.

In the meantime, should it have a void or some kind of ventilation?

ps124

Also, can anyone recommend a good dehumidifier? What size, model, functions do I need?

MX5huggy

You don't need a dehumidifier, yet, that would be treating the symptoms not the causes. Presuming you have a conventional loft (which you seem to have) that is insulated on the "floor" of the loft space (250mm or more of insulation should be there) then the loft should be cold and drafty as said. Condensation may form particularly when it is cold and there is no wind like today.

Hintza

Have you had any wind in the last few weeks? It has been very still with us and the stables/chicken coop has a lot of condensation at the moment.

Once we get a breeze and some air movement it will subside.

Horizon81

ps124 wrote: »

Hi,

Thanks for the replies. Yes I do have ceiling spotlights in all the rooms. We also do use extractors when cooking and bathing (also leave windows open). I wasn't aware that drying clothes over the radiator can cause condensation?

There are no water tanks up there and i'm not really sure whether there is a void or what ventilation is up there. I'll go up there and check.

In the meantime, should it have a void or some kind of ventilation?

When you're drying clothes where do you think the water from the wet clothes goes? It evaporates into the air, increasing humidity levels. Then when the temperature drops, it condenses on cold surfaces. The question is which cold surfaces does it condense on?

If you have a moisture barrier on your loft floor, below the floor insulation then in theory moisture shouldn't make its way into the loft. If you dont, AND you have lots of ceiling spotlights with gaps where moist air can get through then that air will naturally make its way into the loft and condense on the felt and the roof trusses. But then if you stop it getting to the loft then you'll find it makes its way to the next coldest surfaces, most obviously windows and north facing walls in unheated rooms.

Roofs should have some sort of ventilation but plenty dont. You may have eaves vents or ridge vents or even tile vents. I've just got eaves vents, all clear, but still get some condensation. As mentioned, if there's not much wind outside then the vents aren't doing a lot.

As mentioned above, treat the cause not the symptoms, however even with reducing the amount of moisture generated (extractors, opening windows etc) you'll always have some moisture in the house. I ended up buying a dehumidifier, the refridgerant type from Screwfix. It helps collect the moisture from drying clothes but I still get condensation on the windows overnight.

ps124

Hello all. Thank you for the informative replies.

So i've been up in the loft investigating and doing some research. Here are the findings:

Symptoms:
Condensation in the roof is only on the backside and the side extension part. The roof above the front of the house is perfectly dry and fine.

Potential Causes:
Im still not sure what could be causing the condensation. One issue is that we did use a clothes rack in the room directly below the side extension to dry clothes. I've told the missus to stop that now so will see how that goes over the next few days. That room is also my home office so I spend alot of time in there working. i will be opening windows more when i can.
There is also a bathroom with a shower which we always use opposite to my office. This has spotlights which may also be causing the condensation on that side of the roof but we always leave the window fully open during and after showering to allow air to go out.
Someone also mentioned to me your loft hatch. To ensure it is properly sealed and not allowing heat to rise into the loft.

Solutions
I've just purchased a desiccant dehumidifier to help reduce the condensation.
Also I watched a YouTube video that suggested a cheap solution was to these easy vents or wastepipes to open the felt in the roof. This will allow more air circulation and will reduce/eradicate the condensation.

What do you guys think? Reading above, do you think the dehumidifier and opening the felt will do the trick?