Conservatory Damp Help : Who is at fault - Frame Installer or Builder?

[conserved]

Hi from a newbie, please help!

We did an extension recently and at the back of the extension we built a conservatory with the building work done by our builder and coservatory installed by a conservatory company. Over the winter we saw a massive rising damp (please see pictures).

Upon inspection, the builder said the conservatory installer did not use vertical dpc when installing frame which is allowing moisture to sweep through the brick work and contacts the plasterboard (which is touching the external brick work).

However, the conservatory installer is blaming the builder for neither using a vertical DPC under the plasterboard preventing direct contact with external brickwork nor using a vertical DPC cavity closer under plasterboard.

Builder opened up and tried to patch up the exposed external brick work with a vertical DPC but doesnt seem to work- water still ingresses inside when it rains.

Both parties are blaming each other however is causing unbearable stress for us. Please may I have your opinion as to what course of remedial actions are needed?

 

[oldbutnotdead]

Reckon that's rainwater not rising damp.
Your builder should have put insulated cavity closers in all the openings in the wall, plasterboard like that is just a big fat cold bridge.
Are there any cavity trays/weep vents where the conservatory roof meets the house wall? How good is the conny roof flashing?

 

[^woody^]

The cavity should be closed at that location, either by returning the blockwork around to but up to the external leaf and fit a vDPC, or fit cavity closers which negates the need for a DPC. The builder has opted for the later, but not fitted cavity closers! So that's poor work.

Generally, the builder is responsible for the structural opening, and fitting DPCs, and the frame installer just fits the frame. The builder would normally fit the vDPC and let it hang out the wall so that when the frames are fitted, the frames fold it flat against the wall.

However looking at the pictures, the problem (apart from lack of DPC) is that the frames are set too far forward whereas they should be fitted so as to cover the joint between the outer and inner leaf - where the vDPC or cavity closer should be.

In that context, there is some responsibility of the installer to fit the frames correctly, in the correct position and having noticed no DPCs, to bring this to your attention.

Its a simple remedy to insert DPC, squirt some expanding foam into the gap, and replaster. Or retrospectively try and fit some closers.

Bear in mind that this arrangement applies to the top of the wall under the cill too.

 

[conserved]

Thank you both, oldbutnotdead and ^woody^ - your thoughts are much appreciated.

1. Its rainwater not rising damp as we only observe the damp after heavy rainfall

2. The builder accepts that cavity wall closer should have been used but claims he was unaware at the time as the work was carried out by his assistant. He is happy to fit the closer retrospectively.

3. I can also confirm no cavity wall closer is used on the wall under the window cill. The cill itself is wood; am I correct to believe the wooden cill will mitigate to some extent by not transferring the damp across to the inner brick wall? Or, should be wooden cill be removed and cavity closer fitted?

4. I cannot see any weep vents visible anywhere in the external brick work in the building. Not sure if cavity trays were used above lintels or where the conservatory roof meets the house (i'll ask the builder although extension passed BC and external walls are not rendered).

5. The lead flashing above the conservatory box gutter looks ok to me.

Thanks again in advance for any inputs