Whats the best method of locating rafters through Yorkshire flag roof

[dansk]

As the title, the internal is boarded and skimmed over, i cant see a single rafter, anyone know a tried and tested fool proof method of locating the rafters externally.

 

[Gavin A]

is it just plasterboarded and skimmed?

if so, you should be ok if you can get a reference point such as a chimney or velux, but you'll have to do some serious measurements of rafters from inside to out, either using a stud finder (if you're lucky), or Gav's patented knocking method to located the rafters from the inside, then measure up and mark them out on the outside, then drill tentatively and be prepared to have to flash a few misses.

Or the best method is drill through from the inside, having found the rafter first using above methods, then hanger bolts from outside, then touch up the plaster and paint... if you have a good customer.

alternatively.... run away, and definitely run away if it's insulated under the rafters as you're completely stuffed then, unless you fancy removing the flags to find the rafters, which is the other option, but is a bit specialist and the chances are that the wooden pegs will then need replacing or something.

 

[Gavin A]

ps congrats on your can of worms.

 

[dansk]

Cheers Gavin, just as I thought TBH, it's only at quote stage and it's on a newish extension so I'm trusting the rafters should be in good order and equally spaced. I was just hoping there may have been a little trick to it. Removal of slates is going I be the best bet, absolutely no option from the internal.

On a side note, any news back from TS on the invite you sent them?

 

[jerriais]

Hilti PX10 transponder. That's exactly the job it was made for.

PS Selling one second hand if you're interested.

 

[Gavin A]

Hilti PX10 transponder. That's exactly the job it was made for.

PS Selling one second hand if you're interested.

If they can actually see the rafters accurately through yorkshire stone, then I'll happily buy them off you and lend them to dansk if he gets that job, as this has been a recurring problem for us.

anything like that that we've tried has ended up throwing up so many false positives with the battens, foil faced insulation between rafters, plasterboard battens, edges of 3 layers of yorkshire stone etc etc that we've just not been able to rely on them.

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ps no not heard owt from TS