Porch building.

[Cbb8998]

Hi guys, thinking about adding a small porch to my house. I’m a heating engineer. So all the help would be appreciated. It’s not going to be the biggest porch so trying to get as much room as possible. I’m thinking about doing without out a cavity wall. Would a single brick wall with 100mm insulated Silicone render on the external be enough to stop future damp? Or is a cavity wall the way to go?

Only suggesting 100mm insulated silicone render as I’m gonna get that done at the same time on the front of my house as I’m getting condensation from my cold 9inch solid brick wall with no sun.

thanks in advance!

 

[Koolpc]

Cavity would be my choice....

 

[23vc]

Could do block cavity and still get it rendered along with rest of house

 

[^woody^]

Solid with EWI will be fine and damp resistant, and will not waste the space of a cavity wall.

But, consider adding the insulation to the inside face instead, as if this porch is presumably unheated, this will lower/remove the condensation risk and make the porch much warmer by having the warm heat reflective surface on the inside. You could also reduce the total wall thickness by using a thinner but more efficient PIR insulation board.

 

[Cbb8998]

Thanks, it will have water underfloor heating through it to make sure it’s heated. I was insulating the front of the house with 100mm insulation to get it ready for silicone render would you still suggest to put the insulation for the porch internally not externally like I’m doing for the rest of the front of the house for silicone render?

 

[^woody^]

Internal insulation can be better for allowing the room to heat up quicker and keeping the heat longer as the heat does not need to heat up the wall structure first. Hence better for uninsulated rooms.

But it's not a simple case of one way being better than another as there are several advantages and disadvantages of internal and external insulation.

You really should have this properly designed and modelled, as that will mean that all factors are considered, and you get the best - in terms of efficiency, cost and practicalities/disruption.

BTW, by heating a porch you involve building regulations. So you may want to keep it quiet if that's the plan.

 

[Jake2021]

As many know on here I’ve just finished one , if it’s 1x3 metre and upto 3 metres high then it falls under permitted development … if you can afford to loose the space for a cavity I would
Choose that with brick
/ dense block on the outside and thermolite on the inside… I couldn’t do a cavity for other factors
So I did it single Skin but insulated the inside And outside and it’s one of the warmest rooms in the house lol .
I also
Did a pitched Roof With insulation.

Either or will do you but
Don’t scrimp on the foundations and underfloor insulation