Replacing flat concrete porch roof with pitched roof

[sykobee]

Hi,

We're getting an existing flat concrete porch roof replaced with a more standard pitched roof as part of our porch re-working.

The fact the existing roof is concrete was only discovered by the roofer on the day he came to do his work. He said that he would have to break it up and remove it to continue building the roof.

The porch company's surveyor's answer is that the concrete porch can remain and that the new roof can be constructed around it. Of course this is probably because it will cost them a lot to remove the concrete safely (and probably necessitate removing and reinstalling the new porch frontage). They can moan all they like about the extra cost but we have a signed contract that was agreed after he had done his survey so I don't see why we would have to pay for their mistake... but that's an aside.

So my question is - is this actually a viable, reasonable solution - to leave the existing concrete flat roof (around 4ftx2ft) in (stripped of felt, etc), with the pitched roof built around and over it?

There is some wood that is between the roof and the porch frontage that is a little rotten, and IMO should definitely be replaced - which would have been replaced if the roof was completely removed beforehand.

I do have to ask them if their corner support pole is strong enough for a slab of concrete as well as a roof.

Any answers with good arguable reasons would be greatly appreciated!

Cheers!

 

[freddiemercurystwin]

The porch company's surveyor's answer is that the concrete porch can remain and that the new roof can be constructed around it. Of course this is probably because it will cost them a lot to remove the concrete safely (and probably necessitate removing and reinstalling the new porch frontage). They can moan all they like about the extra cost but we have a signed contract that was agreed after he had done his survey so I don't see why we would have to pay for their mistake... but that's an aside.

They have a right to charge for any reasonable extras that were unforeseen. So it begs the question whether they should have been expecting it or not, before you dismiss it. They will just cut corners elsewhere otherwise .......

 

[sykobee]

They have a right to charge for any reasonable extras that were unforeseen. So it begs the question whether they should have been expecting it or not, before you dismiss it. They will just cut corners elsewhere otherwise .......

Personally I think that the surveyor should have seen that the existing roof was concrete beforehand!

Anyway, it appears to have been built into the house and be self-supporting (i.e., presumably have iron bar reinforcements within), so building around it is actually the only logical solution.

 

[sykobee]

Is it standard practice to leave slightly rotten wood (surveyor: "it's just flaky", "it will dry out once the new roof is on") from the old roof in the new roof?

This is the bit of wood that the top of the porch is fixed to, and itself it is attached to the bottom of the concrete slab roof.

How can the new porch be fixed securely to old, compromised wood? And expected to last the expected lifetime of the porch without becoming loose as the wood further degrades?

Edit: Solution found with roofer - longer screws so the porch top is attached through the wood into the concrete.