Building Pathology (L2) Paull Primary School

Question 1

How did you know the wall construction was solid brickwork?

Answer 1

Externally I noticed the wall was constructed in English bond. Internally I measured the door reveal and door frame.

Question 2

Was the damp localised or were any other walls affected?

Answer 2

The damp was localised to the chimney breast within the main hall.

Question 3

How did you know the render was cement based; what issues would you expect with cement-based render?

Answer 3

There was spalled render on the ground which I examined. The colour and strength suggested a cement based render.

Cement render is not flexible and will crack if there are no or little expansion joints.

Cement based render also traps moisture within the building fabric.

Question 4

What were the remedial works you suggested?

Answer 4

I recommended removing the external render and internal gypsum plaster.

I made the assumption that the external wall had suffered previously from spalling and brickwork beneath the render was in poor condition. For this reason, I advised re-rendering using traditional lime.

Internally, I would use a product such as limeLite which is breathable and a natural salt inhibitor.

I would introduce ventilation via vents to the top of the stack and to the chimney breast.

Question 5

What was the cause of the issue?

Answer 5

• Lack of ventilation for the capped off stack.
• Incorrect use of gypsum based products used internally
• Cement based render preventing breathability of the brickwork, trapping moisture internally.

Question 6

How did you produce your estimated costs?

Answer 6

We have a spreadsheet on our server which has rates for removal of render and rendering installation.

I used a day rate and material cost to work estimate for the internal work and providing ventilation to the chimney breast.

Question 7

\What other types of damp could it have been?

Answer 7

Penetrating damp
Rising damp

Question 8

What are hygroscopic salts and why is this important when diagnosing the cause?

Answer 8

Hygroscopic salts absorb moisture in the air. They are a bi-product from the burning of fossil fuels which is why they are common in chimneys.

They can give false readings indicating a damp issue.

Question 9

What was the construction of the school building you inspected?

Answer 9

Traditional brick step foundations with solid brick walls supporting a pitched roof, internal vaulted ceiling.

Question 10

Explain the benefits of using lime?

Answer 10

Natural
Breathable
Natural Salt Inhibitor
Flexible