These are used instead of slates or tiles and underneath they penetrate through the sarking felt.
All of this staining was beneath a hole in the sarking felt leading to the ventilation tile.
If you have an old slate or tile finished roof then it's probable that there is no sarking felt beneath the slates, so it will breathe happily.
If you have the usual black bitumen-based sarking felt you need to incorporate additional ventilation in the roof space.
As the rain seeps through, so it drips on to the sarking
felt laid beneath the roof tiles and slates.
Description: The works comprise the replacement of roof tiling, sarking
, gutters and downpipes; the removal of chimneys; extension of verges; new fences, bargeboards and soffits; replacement of windows, doors and screens, internal cills, apron plates, ingo lining, curtain plates and facings; infilling of existing doorways; and associated works and repairs; all as indicated in the specification and Tender Document (which can be downloaded from this website).
Cavity walls, damp proof courses and sarking
felt under the roof tiles, all contribute to the resistance to damp and the weather.
2 the project shall consist (in summary of): (a) removal of existing slates containing asbestos by a licenced contractor (b) stripping back of roof and removal of damaged rooflights, battens and sarking
felt (c) removal of lean-to flat roof canopy from north-west elevation of school and making good (d) removal and safe storage of natural slates for re- erection (e) insulation of existing flat roof (f) construction of upstands at base of two horizontal rooflights & re-erection of those rooflights (g) recovering of entire flat roof (h) repairs to natural state roofs (i) recover in new sarking
felt and battens areas for artificial slates, including infill rafters to area where 4 no velux roof lights have been removed.
felt catches any water that leaks between the tiles or slates, draining down into the eaves and then into the gutter.
Contract Notice: Repair/Renewal of Roof Supporting Structures, Sarking
and associated coverings, roof drainage including box and other gutters.
Some of our modern roofs only have the bitumen based sarking
felt dressed up through the joint with the lead cover flashing over.
Carpentry - 910 sqm bitumen bituminous sheeting, : - 39 mA timber KVH Nsi deliver, set and assemble, : - 970 sqm roof decking rough sawn 30 mm, : - 1 022 mA sarking
highly permeable, : - 14 mA timber KVH Nsi as joists for wall and roof insulation, : - 555 sqm floor formwork BFU 100 G, : - 910 mA ceiling insulation layer thickness 240 mm 035 stone wool 2-ply cross-laid, : - 53 mA wood preservative for lumber, : - 1 250 mA wooden boards for protection.