Roof gyprock burst located on underside of roof tiles

[C1981]

I had my 30 year old tiled roof cleaned of moss 2 years, hand wire brushed.
The roofer said I had 2 cracked tiles I believed him but I believe he only replaced one tile and it looked a different shape to mines.
Now I have noticed in the loft a burst gyroc board, which is attached to the underside of my tile roof, a common building technique : timber frame house in Scotland.

I got a different roofer today who said there were no cracks in roof Tyles.

Leaves me wondering why the roof gyroc board has burst. Doesn't look wet at burst point and can't see any leeks even though raining. But worried never the less about cause.
Would appreciate any advice.

 

[KenGMac]

C1981, Hi.

Have seen this on a load of occasions, even worse if the boards are made of Cellotex, a brown soft fibre board?

loads of such construction in Lanarkshire and Ayrshire, I digress.

If the collapsed plasterboard has a large wet dark stain then obviously there is a roof leak, in your post there does not seem to be one.

Does the failed Plasterboard have loads of small black spots on either the top or underside of the failed board? if so then there is a very, very high probability that the plasterboard has failed because of condensation, this occurs when moisture vapour enters the loft space from the house. if there is restricted or no roof void ventilation Condensation WILL occur, the condensation will form on the underside of the Plasterboard.

I have found that the Condensation occurs mainly above the Bathroom, where the most of the so called free water, in effect the steam from a bath or Shower occurs.

One question? have you in the last several years had your Loft Re-insulated for "Free" where a company drops by to install a load more insulation into the loft space? what they do not advise you to ensure is that the loft now MUST be ventilated! if not Condensation will occur, I have seen loads of loft spaces where the insulation Contractor has packed the new insulation into the eaves thus cutting off the air flow from the eaves vents, not a good idea?

Back on track again, if the failed plasterboard has a load of small black spots then the condensation could have caused the Plasterboard to fail?

Ken

 

[JohnD]

OOI, we don't usually have sarking boards down here, but I thought it seemed an excellent practice. But I thought it was usually timber or ply? I am puzzled that a material easily damaged by damp would be used in roof construction. The Celotex I have seen is a rigid plastic foam board, usually with aluminium foil skin, not a fibreboard, and my commercial premises have it above the rafters and under the tiles (or it might be Kingspan, I can't remember).

 

[KenGMac]

JohnD, Hi

In general Scottish building practice has for hundreds of years used timber sarking more modern version being ply or Sterling board, but during a huge building boom in the 60s a load of Councils opted to use either as [O/P] plasterboard or indeed 20 mm thick soft board Cellotex, all based [obviously] to conserve pennies.

Having slagged this practice [with apologies to O/P] I have seen dozens of perfectly clean clear and functioning Plasterboard clad roofs, problem is now when the Government sponsored Insulation Contractor who offers [so called] "Free insulation" and do not either advise on or install adequate ventilation into the loft space the much vaunted cost saving in the installation of adequate insulation pales with the roof structure failing because of Interstitial Condensation and un-forgivable lack of information to the home owner, such as the now highly insulated roof space MUST be vented at eaves and ridge

Ken.

 

[C1981]

Thank you for replies.
Just been up in loft burst Roof Gyprock board is above bathroom there are small round damp spots further up on next board and what looks like very small very white round spots on boards All at or below head height. Burst area appears to be dry.

Pulled back old loft insulation from eaves and have discovered that all gyproc boards at bottom of eaves have collapsed.

Further along roof at gable end there does appear to be one large damp patch of gyproc but not burst.
Thanks again and any advice much appreciated.