New flat roof recommendations

[Rav M]

Currently getting a new extension built to rear of flat roof garage.
Going to get a whole new flat roof, roofer is advising to use felt with 120mm insulation but others have suggested using fibre roof as it will keep the new extension area warm.

Looking for advice on what to go for and costs involved or extra cost on top of felt

 

[Notch7]

You will need 120mm insulation, whatever the external finish is going to be, to comply with building regs. The type of external finish wont make any difference to heat loss. A warm roof is better than cold roof generally.

if the roof is a simple rectangle with straightforward abutments, then felt or rubber (EPDM) are good choices.

For a complex roof, then fibreglass is ideal -although still fine to be used for a simple shape roof.

Felt is prob cheapest.

EPDM and fibreglass are about the same price as each other, they have a long life span if done properly.

 

[Rav M]

You will need 120mm insulation, whatever the external finish is going to be, to comply with building regs. The type of external finish wont make any difference to heat loss. A warm roof is better than cold roof generally.

if the roof is a simple rectangle with straightforward abutments, then felt or rubber (EPDM) are good choices.

For a complex roof, then fibreglass is ideal -although still fine to be used for a simple shape roof.

Felt is prob cheapest.

EPDM and fibreglass are about the same price as each other, they have a long life span if done properly.

Thanks - so there is no further benefit for having anything other than felt?

What is required for a warm roof?

 

[^woody^]

others have suggested using fibre roof as it will keep the new extension area warm

Ignore those others. Fibre won't keep anything any warmer.

The main thing with flat roofs/roofers is that those who can only do felt will say "use felt, anything else is crap", and those who have paid for training courses and invested in non-felt systems will tell you their particular system is better than sliced Hovis.

You post is not that clear, but a garage does not need insulating, and your extension should have had the insulation type and thickness specified along with the covering anyway.

Performance wise a good felt system will last as long as any other type. Your problem will be getting a good roofer to install any system properly.

 

[Rav M]

Ignore those others. Fibre won't keep anything any warmer.

The main thing with flat roofs/roofers is that those who can only do felt will say "use felt, anything else is crap", and those who have paid for training courses and invested in non-felt systems will tell you their particular system is better than sliced Hovis.

You post is not that clear, but a garage does not need insulating, and your extension should have had the insulation type and thickness specified along with the covering anyway.

Performance wise a good felt system will last as long as any other type. Your problem will be getting a good roofer to install any system properly.

I see, its basically what the roofer is trained in is what they suggest to use.

Because the new extension is going to be connected to the garage, i though it would make sense to insulate the roof in the garage as that roof is also going to be replaced. The cold from the garage will enter the new extension area as there will only be a small internal door

 

[^woody^]

I see, its basically what the roofer is trained in is what they suggest to use.

Because the new extension is going to be connected to the garage, i though it would make sense to insulate the roof in the garage as that roof is also going to be replaced. The cold from the garage will enter the new extension area as there will only be a small internal door

Generally heat escapes, and cold does not enter.
Garage roof insulation certainly won't make a difference to your situation, and heat loss should be dealt with via the partition wall and door detail.

 

[Rav M]

Generally heat escapes, and cold does not enter.
Garage roof insulation certainly won't make a difference to your situation, and heat loss should be dealt with via the partition wall and door detail.

Oh ok, thanks for that. I will ensure the builder manages this.