Thermal bridge HELP!

JohnoWhits

I am absolutely desperate for a solution.
We moved into our cottage which has stone walls 2 years ago.

•In our main bedroom we had the external walls internally insulated.

•When we moved back into the room we were waking with streaming condensation along the reveals with a 6• temp difference between the reveals and adjoining walls. This damaged the oak window board.

•Found the windows had large gaps either side of the frame so has those filled.

•Took up the tiles from under the window board; had it levelled and any gaps filled.

•We have tried having the windows open, door open, windows on latch with no joy.

•Our son slept in this room last night while we're having work done in his room and we've woken to the exact same problem.

What the hell do we do?! There's not enough room depth wise on the reveals to have insulated them unless we chip them back so there is enough room and then re-plaster (again!).

Do we need to check the windows again externally? Do we need to removed the render on the outside of the house to allow these bits of reveal to breathe?

Do we get someone in to give us another option and if so what type of company? We've had handy men, plasterers, builders etc all give their advice.

Please help I'm unashamedly begging for a solution

FreeBear

With internal wall insulation, you have to carry the insulation around the window reveals to eliminate any cold spots - This insulation has to be on the sides, top, and bottom. Failure to do so will lead to exactly the problems you are having now.

Insulating the reveals with an Aerogel board need not lose that much in space. The boards are an extremely good insulator, the trade off being, they are also a lot more expensive.

Now for a question - With a solid stone wall, did the installers leave an air gap between the wall and insulation, or was a breathable insulation used ?

JohnoWhits

Bear with my knowledge of what’s been done. There were timber batons placed and then celotex then plasterboard. We haven’t had any problems with any other parts of the walls. The problem is there is minimal space on the reveals. When the plaster was taken off to see what was underneath and how far it went back there wasn’t enough space to put even the smallest insulation board on without overlapping the window frame. The plasterer who tidied this up for us (not the person who insulated), said that we may now have to chip back the stone to create enough space to put in an insulation board. The head of the window (roof part) isn’t as cold but that isn’t insulated either as it’s solid stone again under the plaster and under a lintel.

the_lunatic_is_in_my_head

Our house has internal insulation on the external walls but not the reveals.

Obviously it's a bit colder by the windows and some condensation is expected but we don't get an excessive amount on the windows or reveals.

Celotex then plasterboard doesn't sound great for a stone building but Freebear can comment further better than i can.

Do you dry clothes on radiators? Is there extraction in the bathroom and kitchen and is the house heated effectively?

JohnoWhits

Thanks Lunatic for the reply. When the plasterer installed the insulation he contact the manufactures of celotex direct to check it’s application for stone.

We don’t dry any clothes on radiators as we have a tumble dryer in a utility room or dry on the line outside.

We have upgraded our extraction fan in our upstairs bathroom so it’s pretty powerful and downstairs was upgraded to a humidity sensor one.

Jackmydad

The walls are always a bit cooler than the air. Get the relative moisture content up high enough, and you'll get condensation on surfaces only a little cooler than the air.
There's a bit about it here

https://greatlakeswindow.com/window-condensation-causes-reduce-cold-warm-weather/

The only real way to solve it, is to know what the relative moisture is of the air in the room, and what the temperatures of the problem areas are.
Get wet weather like it's been down here for the last few days, and the relative humidity will be way up. So ventilating while always necessary isn't always the answer to condensation.

Slinky

Could you borrow or rent a dehumidifier for a while and see if that has any effect

FreeBear

JohnoWhits wrote: »

When the plaster was taken off to see what was underneath and how far it went back there wasn’t enough space to put even the smallest insulation board on without overlapping the window frame.

Aerogel boards come in a variety of thicknesses, starting at around 5mm. A 5mm aerogel board with (for example) a 6mm thick sheet of plywood on top would be less than most plaster finishes. Slip a 5mm aerogel sheet under the window board, and I doubt very much that it would be noticed.

If the insulation installers fitted battens to the wall, it sounds like they may have left an air gap - This is a good thing as it allows the wall to breath a little.

JohnoWhits

Thanks freebear. I’ll speak to our neighbour who is a plasterer (not the one we used as we didn’t know him at the time) and see what he says. The window board is insulated below now so I hope that shouldn’t be a problem.

We had the window on the latch last night with less condensation on the walls but swapped for condensation on the actual windows.

Hey Slinky. We tried the dehumidifier last time and weirdly it made no difference?!

the_lunatic_is_in_my_head

JohnoWhits wrote: »

We tried the dehumidifier last time and weirdly it made no difference?!

Was it pulling water out the air?

If you have a proper one (nice big unit) and it's not pulling much water then there can't be that much excessive moisture about.

They say we breathe around half a pint of moisture during the night although it shouldn't all just head straight for the windows as other things in the room will absorb it.

However if you put a dehumidifier in the room running all day and it fills up with a lot of water then there's too much moisture from somewhere.

You'd need to insulate the reveals or reduce the moisture in the air (or both).

JohnoWhits

So we tried a big one that did get the water out then tried a little table top one but that didn’t seem to pull much out. When we’ve put the humidity sensor in there it fluctuates from above 65% so not ideal at its best really.