Advice regarding roof replacement (steel structure)

agw_01

agw_01

agw_01

Soldato
Joined
11 Apr 2004
Posts
19,916
I know this is quite a specialist subject, but just in case there are any roofers on here who may be able to offer some advice.

My ~1940s house still has its original roof and I'm looking to get it replaced. The houses on the estate are a mix of private and council but mine is the only one still wearing its original roof. The council replaced all of theirs around 20 years ago.

Fairly straight forward so far... only the roof structure is made out of steel, rather than timber. My roof is constructed of steel trusses and rafters with a metal grid fixed on top and then concrete tiles cemented directly to the frame. It looks fairly normal from the outside.

roof1_1.jpg


roof1_2.jpg


roof1_3.jpg


roof1_4.jpg


I've had a few people out to survey, one of them quoted me a ridiculous price which involved ripping out all of the steel and replacing it with a timber structure. The others have given similar opinions, to fix timber batons to the steel to build an additional structure allowing the use of felt and conventional tiles. My main concern is that they can't guarantee the height of the roof will match with the adjoining property, one of them even saying it could be as much as 150mm difference!

Intrigued to see what the council did with their properties, I had a look in my neighbours loft this morning.

roof2_1.jpg


roof2_2.jpg


roof2_3.jpg


roof2_4.jpg


Not quite what I was expecting to see, large sheets of possibly not very thick plywood screwed straight to the metal structure. I can only hope that there was a layer of felt between the tiles and the boards.

Would the work completed by the council pass currently building regs and should I be seeking building regs approval for the roof replacement given that there could be some changes to the structure of the roof?
 
Last edited:
Any particular reason you're looking to re-roof? Your roof construction is really unusual I'd be interested to see what you do to it. Surely the steel construction is still solid?
 
I’m a building surveyor and have literally never seen that before.

Steel roofs and structures are usually associated with steel framed houses which in themselves are almost completely unmortgageable.

In fact for that reason alone I would be changing the roof to a more traditional structure of timber and tile as when you come to sell it will likely cause a whole world or issues with the banks - they will not like that roof structure at all.

I assume the rest of the house is traditional brick?
 
I've seen that on commercial roofs AND Garages.

Can't see it being a major issue though. They just need to ply and felt, Batten and re tile. Its more likely to be a straighter roof too.
 
Will definitely need Building Control Approval for any works - I would suspect they would want sight of a report from a structural engineer if the steel structure remains in relation to fixings and loadings between any new ply sheathing / coverings etc.

If you do go down the same route as the neighbour have a look into counter battening above the plywood - essentially this means two layers of battens above the plywood and felt at right angles to one another and thus permits any water to run off that has penetrated the tiles (do a search on google images).

Need to consider roof ventilation as well.
 
Thanks for the input guys. I've tried probably half a dozen roofers, all well established and reputable. 3 of them said they didn't feel comfortable with the job while out of the other 3, one of them wanted to remove the steel while the other two had the same ideas on working with the existing structure and adding timber to support the new tiles.

Reason for replacement... as I said, it's the original roof and the only house out of probably 30 that hasn't been replaced. I've had a good look around up there and it all looks water tight and pretty sound. The metal structure is a bit tarnished but solid, it is 70 years old afterall. There are a number of chipped tiles when viewing the roof from the outside, a chimney stack that needs to come down and fascia boards that need repainting, so even if I decide to leave the roof at this stage there is still some work to be done. I only bought the house last year and wanted to tackle the roof first before beginning any major decoration, it was owned by an elderly couple so you can imagine the interior is a *little* dated but I'd be gutted if I redecorated the whole house only for the roof to leak.

@fastwunz, thanks for the reply. I had a full building survey before I bought the house and he mentioned the same regarding the steel structure, however he couldn't find anything to indicate such a structure was present. I also had a wall tie survey and asked them to inspect the cavity and they couldn't see anything either. It's a traditional cavity wall brick built house. House was bought last year and no mention of it by the mortgage compan. I'd imagine probably half of the 30 houses of this style are privately owned. Out of interest, what would a steel frame look like on a domestic property of this age?

@2004typer, counter battening makes sense. I imagine without, if there was a layer of ply, the water would just pool up against the battens and rot the ply boards? Excuse my ignorance on building control, would this be something the council would deal with?

Thanks again, appreciate all the comments.
 
DeanH said:
Did the wall tie surveyor comment on it having a deep cavity? If so have a read of this:

http://www.bisfhouse.com/trusteel-mkii-steel-framed-house/

He may not have picked up on any ties because they all come off the main steel.

A major thing to watch out for is the steel base plates within the cavity corroding either due to condensation or water penetration.
Click to expand...

Said it all for me! Although I would replace the words ‘base plate’ with stanchons - if I were being picky haha
 
Similarly if you do own a steel framed house you have to have it repaired under a guaranteed repair scheme and only when this is done, including any ADJOINING houses, will most lenders give you a mortgage.

To be fair, given the pictures and the brick party wall in the roof space it does indeed look to be brick cavity so you may have dodged a frankly enormous and costly bullet there
 
fastwunz said:
I’m a building surveyor and have literally never seen that before.

Steel roofs and structures are usually associated with steel framed houses which in themselves are almost completely unmortgageable.
Click to expand...

why is this the case? the house has been there for almost 100 years :)
 
psd99 said:
why is this the case? the house has been there for almost 100 years :)
Click to expand...

Good question - basically post war there were way too few men left who knew how to build solid or cavity brick houses. Materials were also expensive and councils and local authorities were looking for a way to build them cheap and build them quick.

Hence the classic steel framed house - cheap to build and put up but beneath the exterior sadly lies some pretty serious issues the most common of which is rust to the stanchions that sit beneath ground level on a concrete base.

They also built ‘no fines’ properties which were concrete framed and with no fine aggregate. You also got similar concrete houses with steel reinforcement which would actually rust from the inside out eventually causing the steel frame to crack the concrete - Taylor Wimpey were one of the first to use the ‘no fines’ method and so you may hear of it called ‘Wimpey no fines’.

Lenders won’t touch them unless they are certain that they have been inspected thoroughly, repaired by a PRA registered contractor with an associated guarantee and that there is a just and active market for them and that the same has been done to any similar properties adjoining them.

They are also often riddled with asbestos but that’s a whole different can of worms.

You can usually spot a Steel framed house as the walls are thinner, the roofs are often sheet metal and the window reveals almost none existent.

Avoid like the absolute plague. Literally.
 
fastwunz said:
Avoid like the absolute plague. Literally.
Click to expand...

I'll stick my oar in again with another reason. The walls are more often than not built off of the floor slabs. All well and good until you see the quality (or lack of moisture resistance) of the infill beneath the slab. Yet you can't renew the slab as the walls sit on it! You're into the realms of asphalting which again is a dying art.
 
DeanH said:
Did the wall tie surveyor comment on it having a deep cavity? If so have a read of this:

http://www.bisfhouse.com/trusteel-mkii-steel-framed-house/

He may not have picked up on any ties because they all come off the main steel.

A major thing to watch out for is the steel base plates within the cavity corroding either due to condensation or water penetration.
Click to expand...

Thanks, that's interesting to read. Sorry, I meant that the surveyor couldn't see a steel structure. He definitely noticed the wall ties as some of them are corroding which I knew about already. The house was built with black ash mortar which I understand reacts with rain water and causes wall tie corrosion.

The link mentions an outer leaf of brick and inner leaf of concrete block, is that typical of all steel framed houses as I definitely have an inner brick leaf. Lathe and plaster ceilings if that has any bearing?

Very interesting comments but from what I've seen and read, would be very surprised if it applied to my house. As mentioned, I paid for a full building survey on the house as well as the lender's own evaluation, neither mentioned it being steel framed and I was able to get a mortgage without a problem. As a lender would usually refuse a mortgage on a steel framed building, if there was any indication of it being present surely they would have investigated further before offering me a mortgage?
 
Last edited:
agw_01 said:
Thanks, that's interesting to read. Sorry, I meant that the surveyor couldn't see a steel structure. He definitely noticed the wall ties as some of them are corroding which I knew about already. The house was built with black ash mortar which I understand reacts with rain water and causes wall tie corrosion.

The link mentions an outer leaf of brick and inner leaf of concrete block, is that typical of all steel framed houses as I definitely have an inner brick leaf. Lathe and plaster ceilings if that has any bearing?

Very interesting comments but from what I've seen and read, would be very surprised if it applied to my house. As mentioned, I paid for a full building survey on the house as well as the lender's own evaluation, neither mentioned it being steel framed and I was able to get a mortgage without a problem. As a lender would usually refuse a mortgage on a steel framed building, if there was any indication of it being present surely they would have investigated further before offering me a mortgage?
Click to expand...

Yes please don’t worry as based on what you have said, you most definitely do not have a steel framed house - just a very odd roof!

Cavity wall tie failure can be somewhat disastrous depending on the extent so you should get it sorted if it’s happening.

Brick and block cavity walls are perfectly normal.
 
I'm very surprised you managed to get a mortgage on that. I'd seriously consider what'll happen if you can't sell it on if you don't keep the maintenance up.

Never seen anything like it outside of a farm building.
 
Maccapacca said:
I'm very surprised you managed to get a mortgage on that. I'd seriously consider what'll happen if you can't sell it on if you don't keep the maintenance up.

Never seen anything like it outside of a farm building.[/QUOTE

Indeed - councils did very odd things.

Hence my advice to replace it with a more conventional roof as soon as practicably possible
Click to expand...
 
fastwunz said:
Good question - basically post war there were way too few men left who knew how to build solid or cavity brick houses. Materials were also expensive and councils and local authorities were looking for a way to build them cheap and build them quick.

Hence the classic steel framed house - cheap to build and put up but beneath the exterior sadly lies some pretty serious issues the most common of which is rust to the stanchions that sit beneath ground level on a concrete base.

They also built ‘no fines’ properties which were concrete framed and with no fine aggregate. You also got similar concrete houses with steel reinforcement which would actually rust from the inside out eventually causing the steel frame to crack the concrete - Taylor Wimpey were one of the first to use the ‘no fines’ method and so you may hear of it called ‘Wimpey no fines’.

Lenders won’t touch them unless they are certain that they have been inspected thoroughly, repaired by a PRA registered contractor with an associated guarantee and that there is a just and active market for them and that the same has been done to any similar properties adjoining them.

They are also often riddled with asbestos but that’s a whole different can of worms.

You can usually spot a Steel framed house as the walls are thinner, the roofs are often sheet metal and the window reveals almost none existent.

Avoid like the absolute plague. Literally.
Click to expand...

My house and indeed my entire estate are wimpey no fines houses.

We had no problems getting a mortgage at all, the bank never even questioned it. They are great houses! Only problem is if you wanna put anything up on an outside wall its near impossible to drill into/thru
 
NoobCannon said:
My house and indeed my entire estate are wimpey no fines houses.

We had no problems getting a mortgage at all, the bank never even questioned it. They are great houses! Only problem is if you wanna put anything up on an outside wall its near impossible to drill into/thru
Click to expand...

It depends on your lender , the market conditions (I.e. if the entire estate is no fines then the lender may have let it go through due to a lack of alternatives within the area) and if the surveyor or bank actually know it’s no fines or not.

Like I said, provided there is a ready market for them and people actually want to buy them then some lenders (certainly not all) May lend on them.
 
You must log in or register to reply here.
Back
Top Bottom