Is my roof safe?

[fabgav]

Bit hard to explain this one but I've tried a diagram.

Its a sort of perspective drawing from outside.

Picture Title

• fabgav
• 16 Jan 2013
• 1

Roof is end terrace half hipped I think.
Brown lines are the edges or roof.
Blue dashed are - I think - hangers? on the 'floor' and run from gable end to party wall.
Green dash are just ceiling joist's
Solid blue sits directly above dashed blue on the roof. I think these are purling?
The brown angle I believe is the hip

Anyway, the 'hangers' are big chunky bits of wood i'd say 3 x 10 or like that, the 'purlins' are the same size and there is a bracing nearer the party wall (blue bit)
At the hip end there is a 'purlin' running from front to back but there is not a 'hanger' below.
Where the two 'purlins' meet the he hip looks a bit odd to me.
The hip is 1 x 7ish and the purlins are nailed to it with no support underneath.
Also the hip only touches the top 4 inch or so of the purlins.
From the bracing part near party wall there is about 2-3 meter (mixing metric and imp. sorry) of unsupported purling.

I will try and get a photo tomorrow, but if anyone can make any sense of this then is it okay? I just seems a lot of wood hanging off the roof and not actually supported underneath.

 

[leeco]

The perlins are normaly supported off the party wall and off the hips. That pic just looke like a normal hipped roof to me.

 

[fabgav]

hmmm, fair enough...
I will get a pic tomorrow though, just to post because despite my brilliant line drawing skills ( ) I may not have got it that accurate.

 

[pinenot]

Your drawing is not very clear, however I think we need to be talking in the same language.
Have a look at this diagram [/img] View media item 55497I think this is close to what you have described. In which case the blue dotted lines would represent part of the hanging system, whilst the upper solid blue lines - are purlins.
The object of purlins are 'by and large' binders/spacers (holding the rafters in their upright position and keeping an equidistant space apart ) , they can also act as load spreaders especially when they are coupled up to something else, in this case some form of angled struts?? that part is very unclear.
It would help if you could tell us how old the roof construction is approx. It would also be helpful if you could get some good pics and post them...pinenot

P.S. are you asking because you want to do some alterations

 

[fabgav]

Hi, sorry i never got around to photos, will try at weekend.

The roof is 1932 council end terrace and has what i think is called a half hip.
ie. there is no 'gable' wall in the loft, just roof.
The angled part that is in the little circle on diagram is where the perlins meet the hip part, possible a ridge board as per you digram.

If there are there to keep the rafter in place as such, these seem to be very large chunks of wood for just that.

I'll get a photo or too asap
A, i already have one on here, maybe I already asked lol

Untitled

• fabgav
• 30 Mar 2010
• 3

The top of pic shows the big chunks of wood with nothing holding them up apart from a 'bender' quite some distance from this corner of the photo.

Untitled

• fabgav
• 28 Mar 2010
• 3

The other end of the perlin sits in partition wall

 

[pinenot]

Borrowed this from the 'evolution of building' site, kinda shows your roof design to a tee!
https://environment7.uwe.ac.uk/resources/constructionsample/Conweb/house_ages/elements/print.htm
However those purlins (not perlins) are something else, I'd tend to ask if the designer knew something more than the rest of us.
However, you asked if the thought "was your roof was safe" and I think on face value it is, but I must ask why you feel the need to ask?
as it has stood the test of time, 75 years +, has it not.

 

[fabgav]

I only asked because was hiding crap up there and noticed it.

Will be converting in the very long distance future but it will be a builders job.

Cheers

 

[joinerjohn]

Nothing wrong with the way the purlin is attached at the hips there fabgav. Think about it, they're already held up by the actual hip rafter.

 

[pinenot]

As joinerjohn says the purlins are already held up by the hip rafters, and the other ends will be built within the party gable wall.
As I expressed the size of the purlins was a surprise, however when we explore roof design evolution and in my own experience, roofs are designed to not only support the applied weight but also wind uplift.
Wind uplift can exceed all other loads over a roofs life span, and whereas we use tie down bars today, yesterdays engineering relied on a full bond of roof timbers to each other and weight. I can only asses that the area of your house has a high wind lift history and your house roof is designed accordingly...pinenot