Trapezoidal / profile roof questions

[Alan Ambrose]

I know this is not a common roof treatment here on 't 'ub, but we're planning to do one of these roofs shortly. I've watched a bunch of YouTube videos (of course) and am finding a bit of variation. Most are US or Australian videos so maybe part of that is due to the local weather.

 

I've these questions:

 

+ I'm seeing eaves overhang from 25 up to 75mm. I'm thinking 50mm for our site, but am interested in anyone else's experience.

 

+ I'm seeing some quite complex examples of folded ends to the flashings - presumably for water resistance and aesthetics. Seems to me a trade off between how well you can do the hand folding (most don't do a great job) and just having cut edges. Anyone do this?

 

+ I'm seeing some use of foam closures at the eaves & ridge but not universally. Seems to me a trade-off between water resistance & ventilation. Any thoughts?

 

+ I'm seeing some use of 'Z-flashings' - sometimes under the ridge flashing instead of foam strips, sometimes along the eaves. Can't really see the benefit? On a quote I got from Cladco they added Z flashings ... but then they also added gloves, a measuring tape and a kitchen sink ... OK maybe not the last one.

[Alan Ambrose]

p.s. are any of the supplier's panels better quality or are they much of a muchness?

 

[-rick-]

Just now, Alan Ambrose said:

p.s. are any of the supplier's panels better quality or are they much of a muchness?

 

Not sure about manufacturers but two things I've found in my research:

1. Can get different thicknesses (I'd prefer thicker but it's obviously heavier, harder to handle and more expensive)

2. You can get different coatings on the panels. I think typical panels have 20-25 year coatings but you can find more expensive options offering up to 60 year coatings. Though the longer lasting coatings might have less colour choice.

 

As usual with me, no practical experience just commenting on research I've done for myself.

[MPH243]

I have fitted some and doing some on a small shed tomorrow.

 

Eaves depth 50mm ish to suit gutter.

 

I try to cut the flashing as little as possible as it's the first area to rust and bending is difficult to make good. How complex is the roof?

 

I have only used the foam fillers they do let a bit of ventilation through but stop most of the insects.

 

Never seen the z profile used for ridge unless maybe more commercial / Industrial buildings.

 

Roofing is normally 0.7mm as it's stiffer when walking on. (If flat enough, it's still a slide when wet)

 

I have bought from Cladco they are good quality and never had a problem, but we are close enough to collect small orders as well.

 

[Alan Ambrose]

>>> How complex is the roof?

 

Very simple, house is a rectangle with dual pitch roof. It does have some veluxes and an SVP and a coupla vents coming through it.

[-rick-]

11 hours ago, MPH243 said:

Roofing is normally 0.7mm as it's stiffer when walking on. (If flat enough, it's still a slide when wet)

 

When I mentioned thickness I was thinking of 0.7mm as the standard but you can get thicker. 0.9/1mm IIRC

[markc]

Eaves over hang or “cut back” is generally 50 or 75mm which is usually sufficient to keep water from travelling back on the underside. Fold ups at eaves are done to prevent blown water going over the top edge if not stopped by the filler. Eaves fold downs are more aesthetic than functional.

eaves flashings are usually L shaped but do often have a small kick in for looks.

gutter flashings can look nice … or terrible! And tend to collect leaves etc..

[Alan Ambrose]

@markc - Thanks, do you have any thoughts / recommendations re good fillers? Are there any goodonea that work in stopping driven rain / critters but allow OK ventilation?