Simon R

Blacho Trapez steel standing seam roof - first experience

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We've just finished our standing seam roof using a roof from Blacho Trapez. The roof cost less than half the quote we had from Catnic for a Tata Colorcoat Urban. At around £15/m2 for the roof sheeting it represents good value. Buy the time you add eaves and barge detail you can add another 1/3 to this figure. Transport will add significantly as a lorry from Poland will cost nearly 2k so sharing transport is important.

This post is to let others know how we got on with the roof and hopefully help when they are considering which standing seam roof to go with.

This is our first self build and we have no first hand knowledge of any of the other standing seam systems on the market.

We came across the roof by chance when another buildhub member @Patrick posted that he was looking for other members who would help share transport costs. Patrick knows far more about the roofing system that we do and is now in the process of formalising an agreement with Blacho so that he can help others order and import roofing products from Blacho.

Blacho are based in Poland where steel roofs are far more main stream than here. They have many roof designs, we selected their Retro 25 system which is very similar to the Tata Colorcoat Urban system. Once you have selected the roof style, you then select from a range of 8 input sheet materials. These range from a basic sheet offering just 10 years to a Krupp Pladur sheet offering 50 years protection. Included in the range is Tata HPS200 ultra. The price of the Pladur sheet is not a lot more than the HPS200 and it was our first choice. However the Pladur product is not a know quantity here, so we selected the Tata option which has a 40 year warrantee and widely known so won't cause any undue questioning form building controls and insurance.

Here is a link to the roof catalogue:BT-Katalog-2018-EN inch revised.pdf

Ordering a roof is more complicated that you might think, with soffits, barge boards , eaves edges, pitch, etc to consider. After a couple of iterations with Patrick doing the communication with Blacho we ended up with a roof order.

The roof comes palletised, so you need plenty of hands to help unload if you don't have plant on site.

Installing the roof is pretty straight forward, I'm not going to attempt to duplicate the resources provided by the manufacturer.

The following is a condensed “lessons learned”:

  • You may think your roof is square, it's not. You can lose small inaccuracies when dealing with tiles. Big sheets of fixed size show every millimetre of any discrepancy.
  • Check you can get the sheets to the area of roof they will be installed on. We didn't and three 7200 sheets we had for the rear roof ended up being cut and joined. If we did it again we would not have any sheets over 6500, they just get too fragile.
  • Get your datum lines right, check and recheck. We used the time honoured and infallible 3-4-5 rule to get our datum lines. For the most part this worked fine but on one section of roof where we started with a thin strip to get the even sheet distribution, we failed. This resulted in a 10-15mm error over 3500. It was the area round the roof lights, which themselves turned out not to be square in the roof either!
  • Avoid sheet joints if you can, they are fiddly to make and add to the installation time.
  • Use string guide lines. We didn't and paid for it with small discrepancies that could have been avoided. The apex of the roof is one area that we found difficult. It looks OK but does not bear close inspection.
  • Use a sheet nibbler. Unless your really skilled with  tin shears they make getting an acceptable finish achievable.
  • The devil is in the detail as they say..getting the barge boarding and eaves edges right takes quite a while. We opted for a “Swedish eaves” edge that involves folding the roof sheets over the eaves former. Great for preventing any wind getting under the sheets but makes getting the guttering correct difficult. The rain runs off the sheets at quite a rate and can easily overshoot the guttering edge or get caught by the wind and blown over the back edge. We ended up running flashing to the inner gutter edge. It can't be seen and should be a belt and braces solution.

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Hello SimonR

Does this steel cope with a curved barn shaped roof, or a curved drum shaped building with the seams running vertically??

Do you know the minimum radius of curvature?

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2 hours ago, Simon R said:

[...]

You may think your roof is square, it's not

[...]

 

That trauma is done. 

Good to see someone else facing the same issue. 

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30 minutes ago, Grendel said:

Hello SimonR

Does this steel cope with a curved barn shaped roof, or a curved drum shaped building with the seams running vertically?? 

Do you know the minimum radius of curvature?

Good questions to which I don't know definitive answers. I didn't spot any curved sections in the catalogue, but they do steel "pan tiles" and several other product that could lend themselves to more complex roof shapes.

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Posted (edited)
15 minutes ago, Simon R said:

Good questions to which I don't know definitive answers. I didn't spot any curved sections in the catalogue, but they do steel "pan tiles" and several other product that could lend themselves to more complex roof shapes.

They don't do curved, it s tricky as you would need to "curve" the standing seam. Not really possible premade, only on the roof (possibly with heat?). The sheets will take a slight curve of a few degrees but nothing that would count as a "curved roof". Same for all the other type of metal sheets, to my knowledge.

Edited by Patrick

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