Hi, I have recently purchased a mid terraced house and due to a few problems with the property they have held a 6000 pounds retention until the relevant works have been carried out. One of the problems is a roof to a single storey extension, the mortgage lender has said it needs completely removing and replacing to meet regs. My question is whether or not I would need to replace the wooden lintel above the window and would it be ok to use another wooden one, if it does need changing.

cheers

what you have is a poor quality "lean to"
no insulation probably no damp proof as scruff says probably knock it down and start again
you need to ask your morgadge provider what exactly is required as they are calling the shots so they need to be satisfied to release the funds

What sort of roof do they want you to fit?

It looks like this is just a simple lean to, so are you planning to fit a twin wall polycarbonate type of roof? If so it has very little weight and you wouldn't need a lintlel, although you may need to fit a length of timber on top of the windows, across the entire width of the extension, to spread the weight over all the windows.

This is as long as the back door opens into this room rather than the back door opening out of it. If it opens into the room then it is more or less a conservatory and building regs are not stringent. If the back door is in the extension then the extension forms part of the house and you would need a much more robust roof design, which I think you would find difficult to fit on the window wall you have. Then you would need building permission from the local council and from the look of the pictures it would cost you thousands to do properly.

The door does open into the room, but that is the back door, does it matter what sort of roof I put on? Polycarbonate? Or wood construction with insulation?

No they just want it to meet regs, Doesent need certifying

Planning permission would be needed if the new roof is raised more than > 150mm but there is still the question of what building regs does it need to meet?

If this is classed as a conservatory then the existing roof probably meets the regs and you don't need to do anything but minor repairs such as replacing the broken glass. On the other hand if it's not a conservatory then you might have to do a lot more than replace the roof.

From here it looks like it meets the rules for a conservatory already so I'm puzzled why the mortgage co think you need to do anything.

There are other reasons why different regs may apply....

In some cases the flat roof of an extension is used as a fire escape route from the main part of the house. eg out of a window, across the roof of the extension and down onto the ground. In that case the roof would have to be a lot stronger to allow it to be walked on. Should be possible to check if this applies.

In some cases an extension close to a boundary has to meet certain fire regulations that might have implications for the amount and type of glass used.

I think you need to ask the mortgage co why they think the existing roof doesn't comply with the regs. The reason they give should help identify the work required.