Precast Insulated Walls vs ICF

MariaDi · Jan 24, 2024 10:58 pm

Hello everyone, I'm currently grappling with the decision between ICF and Precast Insulated Panels Like ⋅ Add a comment ⋅ Pin to Ideaboard ⋅
for the construction of my new house, particularly for external walls and floors. Although I am leaning towards precast insulated panels, I have some unresolved queries. I intend to build a two-story house with internal dimensions of 8.5m x 8.5m. The attic is envisioned to be 'habitable,' featuring a spare room and a utility room. I am contemplating raising the walls by 0.5m, essentially creating a nearly 2.5-storey structure. Additionally, I am considering a roof pitch of either 8/12 or 7/12. Here are my questions:

Does anybody have an idea (with a large approximation) of the potential differences in cost and completion time between ICF and precast insulated walls?
For the external rendering of precast insulated walls, is it adequate to paint the concrete, or is another type of rendering (such as stucco) necessary?
If rendering is required, what would you pick for optimal durability and maintenance? Should a membrane be installed between the concrete and rendering to prevent trapping humidity/water?
Concerning precast insulated walls, is rendering necessary on the interior side, or is it possible to paint the concrete directly?
Regarding the floor, if I choose hollow core slabs, are load-bearing walls necessary on the ground floor, considering a span of 8.5m from wall to wall? Additionally, approximately how thick would the floor be?

I appreciate any insights or advice you can offer. Thank you

alexp79 · Jan 25, 2024 2:42 pm

I don't think that standard hollow core slabs will be able to span across 8.5 m, you would need to support them either with internal load bearing wall or with structural steel or concrete beam.

You would need to seal concrete from the outside, ideally with render and then you would have to decide how you arrange communications and what you are planning to do about internal finishes - chasing through concrete is really not fun.

The main problem I foresee is that concrete is not a very breathable material, so you would need to rely heavily on mechanical ventilation, managing humidity will always be a problem in a concrete house.

gommeqld · Jan 26, 2024 6:23 pm

Good questions but the best answer will be obtained by visiting (ie: interviewing) a couple of house designers and/or builders and ask them.
You may find it challenging to locate a designer or builder who has any experience in both build methods.
It may be that you have to ask a couple of architects for their opinion but that would be my last choice.