Porch

[Magrah]

Hi All,

I have a porch that's about 1.5 meters wide and 1 meter deep from the house. The porch has been built with single brick have way with batten and T&G cladding on the inside half way. Then the rest is surrounded by new 18mm double glazing as is the porch door.

The roof is 4 x 2 with non breathable felt and tiles.

I would like to insulate the roof and was just going to stick 100mm mineral insulation between the roof joists. However I know on a normal rook you have to maintain an air gap. As this is such a small roof does it matter?

To maintain an air gap i'd had to find some way of letteing air in at the facia and perhaps tile vents near where the roof hits the house wall. Not seen this before so perhaps i'm making mountains out of mole hills and should just do the 100mm insulation route!

Thanks

 

[noseall]

Why are you insulating the roof?

 

[Magrah]

Hi

To save heat, I have a hardwood door into the entrance to the house with just 6mm glazing, so we lose quite a bit of heat through that door. Its two fold also, the sun hits the porch in the summer a lot and its like a sauna in there when you open the door!

The question is do you need an air gap or is the roof too small to worry about?

 

[noseall]

Does your front 'porch' door open into a separate enclosed porch or does it open into the main dwelling?

Is this separate porch heated?

 

[Magrah]

Hi, the front wooden door opens into the house to go into the porch and the porch door then opens into the porch to let you out if that makes sense?

 

[noseall]

Ok, so you have an enclosed porch separated from the habitable dwelling by an external door.

Is your intention to heat the porch?

If so, insulating the roof alone will be pointless. You could fit some insulation to the roof void but it will be a token gesture.

 

[Magrah]

Hi

My intention is not to heat the porch but there is significant heat lost through the door and the roof is just felt and tiles whilst the rest is 18mm double glazing and door. So the idea would be to help limit the heat lost or slow it down. Does that make sense?

 

[noseall]

Would it not be a better idea to improve the door separating you from the porch or at least encourage people to keep it closed.

Reducing drafts, i.e ensuring all openings are as airtight as they can be will go a long way to ensuring your house is warmer.

 

[Magrah]

Replacing the door is not really an option, besides putting another multipoint locking double glazed door in seems a waste of time (by the way we purchased the house like it). Hence I thought the porch is pretty well insulated bar the roof. Although insulating an unheated space does not make sense it will limit the heat loss in the winter as heat will be escaping into a insulated void.

 

[Shortee]

Hi Magrah - I am just in the process of doing the same, but in my case there is no door between the porch and main house - there is also a radiator in the porch. Therefore it makes a lot of sense to insulate the roof cavity.

In your case there should be a small benefit, but the door between the house and porch, even if single glazed, will stop some heat escaping (when closed). But, if it is easy to put the insulation in you might as well, given the low cost of rock wool type insulation (when on offer).

Building Regs require the loft space to have adequate ventilation. This is to avoid moisture in the air condensing and causing damp issues. This problem will be worse where the space under the loft (e.g. the house!) is heated - warm air can hold more moisture, but when it gets into the loft space, i.e. above the insulation the air is cold, so the air cannot hold as much moisture and it is released as condensation. If you use porous insulation e.g. rock wool then such moisture will reduce its effectiveness as well as causing timber to rot etc.

In your case, given the porch is not heated and separated from the main house by a door, such condensation in the porch loft may be minimal. However, I would recommend you make sure there is some ventilation e.g. under the eaves - or perhaps in the front fascia using a discreet grille (insect proof ideally!). You might consider alternatively using non-porous insulation such as Celotex/Kingspan board insulation. This won't stop condensation but at least won't be compromised by condensation.

My conclusion is that it would be advisable to ensure there is some ventilation, although the risk of condensation may be small given the lack of heating in the porch.

Hope that helps.

 

[noseall]

I am just in the process of doing the same, but in my case there is no door between the porch and main house - there is also a radiator in the porch. Therefore it makes a lot of sense to insulate the roof cavity.

....and therefore it is not a porch.

Which means (as far as reg's are concerned) that the floor walls and roof all need to comply.

 

[Shortee]

Anyone looking at it would describe it as a porch - including the surveyor when we bought it - although I appreciate that build regs would class it as an extension (as ridiculous as that is). However, it was constructed decades ago. I agree the structural components should comply - or at least they are required to if it was a new build or was being substantially altered - but I am doing the porch loft because it makes economic and environmental sense, not because any structural or significant alterations are being made.

 

[noseall]

Anyone looking at it would describe it as a porch - including the surveyor when we bought it.

Then your surveyor is a twit and wrong, it is an entrance hall.

I am not trying to discern what is the correct description other than pointing out to people viewing this post that connies and porches up and down the country are losing heat and are an inefficient alternative to a full reg's space and they contravene reg's.

Cheaper and more convenient yes, but still vulnerable to these extremely cold winters we are having lately.

I would not use that surveyor again either.