Roofer cutting corners? Felt roof on top of steel roof?

Hi folks,


I have a large concrete built shed. It was built by my dad about 15 years ago, so entirely a DIY effort. He threw a corrugated steel roof onto it, and it's recently started leaking. Which is fine. Owes me nothing at this point.


I have an extension, which has a large flat, felt roof. It's about 4-5 years old, was done by a roofer I had seen previous work of, and came recommended.

So I got him to price redoing the shed roof, from metal to felt. My original assumption would be that he'd take the steel roof off, back to the joists, and put some ply down on the existing joists and felt over it, yada yada.

After he looked at it, to quote for it, he said i'd be better off just leaving the steel roof there, and doing the new roof over it. Which was fine with me. I figured he meant he'd build a new frame over the steel, and then roof it as normal.

Instead, what he has done, is put the plywood straight onto the existing steel roof. He started today, so he has the ply down, and he has it covered in plastic/membrane. He'll be back tomorrow.


My thinking here is that this is a bit of a flawed plan, as, firstly, the steel will have movement in it (it has flexibility, albeit, not lots of it) but presumably if you now walk on the plywood it'll sink if it goes across a bit of steel with movement in it, and as a result you'd invariably end up cracking the felt and your roof would be knackered in no time?


Now as I say, he seems trustworthy, he's well known locally, and he has been at this for years, so I'm not really one to question him. On the plus side, he's aware that he won't get paid until the end of the month, when I get paid, so I'll have the roof for a couple of weeks before paying him in full (he has a deposit at the moment).

Just looking to see if anyone here has any advice? Should I leave him at it and see what happens, or should I make it known I'm not wholly happy with what I view as corner cutting?


Would love to hear from anyone with any bit of knowledge here.

Cheers folks.

Calahonda52

is the steel corroded or just leaking here and there.
how thick is the ply?
Is it fixed to the joists or the steel?
The steel will give more support than the ply on its own so maybe you are over thinking it.

GreeBo

Would you have walked on the roof before?
For me it would entirely depend on the state of the steel roof, if it's not structurally sound then it should be removed for the reasons you outlined, if its sound but leaking then overboarding it is probably ok, but I would want any rust etc dealt with so that it wasnt rusting away underneath the new roof.

Car99

What type of corrugated sheeting is on the roof? Galvanised corrugated or something else?

Sorry for slow reply folks.

Yeah the steel was a galvanised corrugated steel I believe (I don't know my steels too well, but I'm fairly sure that was it). Hadn't really got much rust on it (none that I can really remember) and you could indeed walk across it. However, there were parts were it had sagged a bit (from being walked on presumably).

I ended up not saying anything to the roofer, as he's been doing roofs in the area for 20-30 years, so I figure he'd know better than I would (hence posting here) but the roof was finished yesterday and you can see an odd looking 'dip' in the roof now that the felt is on. I will have to get onto it and have a look properly, as I've not stood on it yet, but from ground-level looking up at it, it has a very odd shape.

I'll have to run the hose on it later on after work and see is the water pooling or does it run off cleanly enough.

From reading the replies here, it seems he was alright to go over the roof that was there but I'm just not wholly convinced that sticking the ply on an old steel roof, without at least giving it a small extra bit of a 'tilt' with a new subframe, was the best idea. I'll report back later, and hopefully I'm wrong, but I fear there will be water pooling.

GreeBo

Ah I didnt get from your OP that the shed also has a flat roof.
I wouldnt bet your money on a flat felt roof tbh then add in that it now contains a dip that holds water...

GreeBo

GreeBo wrote: »

I would bet your money on a flat felt roof tb.

I'm not sure what you mean there, but to clarify - I like flat felt roofs. I think once they're done properly, they last ages and rarely give trouble.


They have a bad reputation, but my personal experience with them has been good. I'm just not sure how I feel about this particular roofing job.


Roofer may well have already checked water run off, etc. and it could be just my view of the roof being a bit distorted, looking up at it, but I definitely want/need to check for myself.

GreeBo

Deleted User wrote: »

I'm not sure what you mean there, but to clarify - I like flat felt roofs. I think once they're done properly, they last ages and rarely give trouble.


They have a bad reputation, but my personal experience with them has been good. I'm just not sure how I feel about this particular roofing job.


Roofer may well have already checked water run off, etc. and it could be just my view of the roof being a bit distorted, looking up at it, but I definitely want/need to check for myself.

Oops, typo, edited now!
I *wouldn't* bet your money on it.

tbf they have a bad reputation as they often go wrong.
Having standing water significantly ups the waterproof requirement of any surface, it also opens the door to cracks from freeze/that action down the road.

I would always favour getting water to run off, it means you have much more leeway around waterproofness.

If you do have puddles "filling" them with pebbles can help (it also helps protect the felt from the sun.

..Brian..

I don't see a problem with this tbh. As long as the structure is sound and by the sounds of it, your man wouldn't leave it there is it wasn't. I'll be doing a very similar job to my workshop roof in coming months.

GreeBo

I got home late from work, today, so didn't get the chance to look over it. Will have to be tomorrow.

GreeBo wrote: »

If you do have puddles "filling" them with pebbles can help (it also helps protect the felt from the sun.

Well, he hasn't been paid yet, so if there are puddles he'll be the one to deal with it. I'm not a difficult customer, or hard to please, but I'm not gonna willingly pay up for a job if it's not done right.


I don't mind a small bit of pooling. I've read water that evaporates within 48 hours is generally not considered 'standing water', but if there's a deep recess and I've a swimming pool on the roof, he'll have to fix it for me.




Brian could well be right, though.

policarp

Deleted User wrote: »

Hi folks,


I have a large concrete built shed. It was built by my dad about 15 years ago, so entirely a DIY effort. He threw a corrugated steel roof onto it, and it's recently started leaking. Which is fine. Owes me nothing at this point.


I have an extension, which has a large flat, felt roof. It's about 4-5 years old, was done by a roofer I had seen previous work of, and came recommended.

So I got him to price redoing the shed roof, from metal to felt. My original assumption would be that he'd take the steel roof off, back to the joists, and put some ply down on the existing joists and felt over it, yada yada.

After he looked at it, to quote for it, he said i'd be better off just leaving the steel roof there, and doing the new roof over it. Which was fine with me. I figured he meant he'd build a new frame over the steel, and then roof it as normal.

Instead, what he has done, is put the plywood straight onto the existing steel roof. He started today, so he has the ply down, and he has it covered in plastic/membrane. He'll be back tomorrow.


My thinking here is that this is a bit of a flawed plan, as, firstly, the steel will have movement in it (it has flexibility, albeit, not lots of it) but presumably if you now walk on the plywood it'll sink if it goes across a bit of steel with movement in it, and as a result you'd invariably end up cracking the felt and your roof would be knackered in no time?


Now as I say, he seems trustworthy, he's well known locally, and he has been at this for years, so I'm not really one to question him. On the plus side, he's aware that he won't get paid until the end of the month, when I get paid, so I'll have the roof for a couple of weeks before paying him in full (he has a deposit at the moment).

Just looking to see if anyone here has any advice? Should I leave him at it and see what happens, or should I make it known I'm not wholly happy with what I view as corner cutting?


Would love to hear from anyone with any bit of knowledge here.

Cheers folks.

You should have had a plan before bringing in a builder.
But now that you trust him, has he shown you shown you some previous.

policarp

policarp wrote: »

You should have had a plan before bringing in a builder.

How do you mean? It's a roof replacement?

So i haven't been able to really get a proper look at the roof over the last few days. It was either covered in snow or ice anytime I was able to get a look during daylight.

However, temperatures have risen, and through most of last night and this morning, there was heavy-ish rain. The rain tapered off and ended about two hours ago. I took these photos looking out the house window at the roof (hence they're not the greatest) but from looking at it now, and the amount of pooling, I don't feel I need to be worried or concerned about it. It seems the pooling is tiny and fairly acceptable for a flat roof.

Before I actually had any water on the roof, perhaps it was an optical illusion, but the roof looked like it had a dip in the centre, which is what made me post here, in concern, but thankfully, actual rain has demonstrated to me that isn't the case.

the_pen_turner

you have a great fall in your gutters anyway

the_pen_turner

the_pen_turner wrote: »

you have a great fall in your gutters anyway

You'd think that. Just as it goes out of camera shot on the left, it starts to dip down again :rolleyes:

So water pools in the left until it gets an inch or so high, enough that it can get over the high point in the centre, and drain off to the right. I promise to fix it this year, though. Maybe.


EDIT: Though I think the fall in the gutter is a bit of an optical illusion, as the roof itself seems to dip towards the left of the picture. Which is one of the things that originally concerned me.

GreeBo

Its strange that the pooling is in such a regular pattern, but as you say, the depth of the pools isnt anything to worry overly about imo.