Insulation panic!!!!

marielle

Hi guys, sorry newbie alert here!!! I am in the process of building my house and my father in law who has had a lot of experience building houses but is now retired is actually doing most of the work. I am going for Underfloor heating powered by a heat pump (don't know yet if it will be ground source or air source - any advice on which to go for is more than welcome - ) and i want a heat recovery unit which means that I need an airtight house. All these fandangle things I'm afraid are not compatible with his ideas of how to build a bog standard house and I am now really worried that he will be making the wrong choices in terms of insulation and its installation and the likes. Could yous tell me the do's and don'ts in this area? Just to give you an idea, we are almost finished slating, the windows are all in so the next step will be to sort out the heating system and underfloor heating as well as the insulation that will go with it. I'm just very nervous he will go for something that will jeopardize my investment in these costly systems. Help!!!!!

muffler

You've posted that already in another thread and i hope you are aware that its not the done thing to post the same thing twice for obvious reasons. I should give you a red card but seeing as Im in a good mood i will leave this and delete your other post.

Please familiarise yourself with the charter and general boards.ie rules.

Viking House

First you need to tell us what stage your house is at.
Is the floor poured?
How much insulation did you put under the floor and what type of insulation did you use and what thickness's did you go for.
Do you have insulation in the walls? What type and thickness?
Have you insulated the roof yet?

marielle

Hi again and thanks for replying. We have cavity insulation in the form of a grey polystirene type insulation that is 60mil thick.
The ground floor is simply the concrete foundation and the top floor is made up of concrete slabs. Nothing is poured on it yet so no insulation on the floors yet and the roof is not insulated either yet. I have to decide on these though hence my question... Thanks for any advice....

Viking House

marielle wrote:

Hi again and thanks for replying. We have cavity insulation in the form of a grey polystirene type insulation that is 60mil thick.
The ground floor is simply the concrete foundation and the top floor is made up of concrete slabs. Nothing is poured on it yet so no insulation on the floors yet and the roof is not insulated either yet. I have to decide on these though hence my question... Thanks for any advice....

Are the slates and roofing membrane on yet?
Is the concrete poured on the ground floor? I would recommend 25-30cms of Polysterene under the slab if it is still possible.
The best way to insulate your walls now is to fill the cavities up with polstyrene beads and put another 5/7cm of Polysterene on the outside of the walls and plaster directly onto the insulation.
Are the windows in yet?

galwaytt

I'd disagree with the external polystyrene insulation - dryline inside instead.

I personally would use external insulation so as to use the walls as a "thermal store" to regulate the internal temperatures.

Viking House

galwaytt wrote:

I'd disagree with the external polystyrene insulation - dryline inside instead.

The proper drylining detail is to leave a ventilated cavity between the drylining and the wall. There should be a vent a few inches from the bottom and a few inches from the top to achieve an airflow.
Otherwise you will get fungus and mould growth between the wall and the insulation.
This airflow between the two layers of insulation cuts the insulation effect in half.

When you dryline, the areas where the middle floors and middle walls meet the outside wall are not insulated, leading to cold bridgeing. So you are only insulating 90% of the wall when you dryline.
So 2 inches of insulation outside is as good as 5 inches inside.