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Mass Concrete Roof

Please contact us if you would like to receive a quote from one of our approved contractors.Mass Concrete Roof Diagram

General

Concrete roof decks (A) tend to have a high moisture content which can lead to blistering in warm weather and breather vents should be incorporated to allow the moisture vapour to escape.

Insulated Concrete Roof Deck

  1. Sweep roof (A) and remove all sharp stones and grit.
  2. Paint the Deck with 2 coats of Bitumen Primer (B).
  3. Loose lay a layer of Gruver* (C) perforated felt butt joining in preference to lapping.
  4. Set out a double wall breather vent (L) according to manufacturer's instructions, usually 3 to 4m apart.
  5. Loose lay Multiplast 40200 (D) with an 80mm lap which should be carefully torched. The sheet should be cut to fit nearly over the neck of the breather vent (C).
  6. To secure the above the perimeter sheets should be torched to the deck (A) for the first 50 cm from the edge.
  7. Set out insulation boards (E) which should be pre-faced with a glass-fibre based bituminous felt, and fix through to the concrete deck (A) with mechanical fixings (F) according to the manufacturer's recommendations.
  8. Loose lay a layer of Gruver* (C) perforated felt butt joining in preference to lapping.
  9. Set out breather vent (L2) according to manufacturer's instructions.
  10. Torch on a layer of Dermabit 30160 (G) being careful not to overheat but still ensuring a partial bond to the insulation board (E).
  11. The cap sheet should be either Casali Dermabit Extra 4170 smooth or Casali Dermabit Extra 43170 mineral (H) and this should be fully torched to the underlay and the 80 mm laps should be staggered so as not to lie on top of the laps of the underlay (G).
  12. If Casali Dermabit Extra 4170 smooth is used it should be painted with 2 coat Aluminium Reflective Paint (I) preferably 4 to 6 weeks after the felt is laid.

Please contact us if you would like to receive a quote from one of our Approved Contractors.

*In case of roofs exposed to high winds, it is better to delete the Gruver and loose lay the underlay (G) fixing it with mechanical fasteners (F) through to the deck.

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