A a foaming roof is a slate roof shape. It has evolved as a form of vernacular architecture associated with the West coast of the British Isles.
Roof grouting is distinguished by having an overall layer of cement rendering.
Video Grouted roof
Conventional slate roof
The conventional slate roof consists of a thin whiteboard, hung over a wooden slats. Whiteboard is hung with a wooden peg through the hole at the top of each slate. The stakes stop the slate slipping down, the whiteboard weight on top holding the slate down. The roofs then replace the pegs with iron spikes that are moved into the battens, but the nails are always a hook and weigh higher than the one that holds the roof covering down to the frame. A nail mine is also used, long enough to bend the laths from the inside. Lately it developed into strips that were cut from lead sheet.
Such a roof is common and very well known in Wales, where high quality slate from North Wales is exported worldwide. Because of the high quality slate it can be split very thinly by the experts and therefore provide lightweight, durable roof coverings against harsh weather. Where a local slate is used instead, it is of lower quality than the Snowdonia slate and so the roof design may be less successful. In particular, lower quality slate should be cut into thicker, heavier slates to maintain sufficient strength, thus giving the roof a much greater weight.
Failure on the slate roof
The main means of failure on the slate roof is when individual whiteboards lose their peg attachment and begin to slide out of place. This can open a small gap above each row.
The secondary failure mode is when the whiteboard itself begins to break. The bottom of the slate can be loose, giving a crack under the slate. Generally small areas and stress above the nail hole may fail, allowing slates to slip as before. In the worst cases, the slate may break in half and disappear altogether.
A common improvement for slate roofing is to apply 'burning', fillets mortar under the blackboard, stick it to the batten. This can be applied either as an improvement, to withstand a slipped whiteboard, or pre-emptively on the construction.
Where the blackboard is very heavy, the roof may begin to split along the roofline. It usually follows the decay of developing and weakening internal wood, often as a result of bad ventilation in the roof space.
Maps Grouted roof
Grouted Roof
Where the roof has begun to fail entirely, it may be 'grouted' to prolong its working life. This is not a place repair, but the overall treatment is applied to the entire roof. A thin wash of mortar or rendering is applied on the roof. It fills the gap between the blackboard and also covers the surface of the board. Grouting has two distinct visual effects: the different edges of the slate slate to the monolithic roof panel and also, because the grout is pale white, the paler than other building materials seen, the roof becomes much more prominent.
Grouting is seen predominantly along the western coast of England, especially in Pembrokeshire in South West Wales and on the lower levels of the Isle of Anglesey, Cornwall and Devon. It has also been used, primarily as a sealant, on porous stone slabs such as the Permian sandstones of Dumfriesshire.
Grouting was developed as a repair technique. The roof may be trampled several times, each time the layers become thicker and more rounded. Finally the weight of this extra rendering becomes too much for the roof structure and the roof can fail to be fixed by splitting on the ridge.
The roof of Pembrokeshire's ropes
The Grouted roof is most typical in Pembrokeshire and is thought to form part of the regional vernacular architecture.
The hallmark of the Pembrokeshire's roof style is a number of prominent vertical protrusions on the outside of the roof. This is caused by a barbed wire that runs on the roof before installing. The wire can be firmly attached to the structure and the barbs on the wire act as a mechanical lock to keep the grout in place. Over time and repetition of grouting, the wires disappear under the backs that accumulate. Barbed wire is used because it is readily available to remote farming communities and well done. It was not manufactured until the 1870s and the style of this roof is newer than the first use of grouting, even with cement.
Lime mortar vs. Portland cement
There is some debate about the materials used to build the roof of 'original' grouting. Clearly Portland and modern cement-based renders have been used most commonly in the last century. Portland cement first appeared in the 1820s. Prior to this, lime plaster will be used, especially in rural areas where lime burning is a local industry through most countries.
Many sources claim that lime plaster was used initially, by moving to cement making when they became available in modern times. Others claim that the roof mounting technique is only developed with the advent of modern cement that is cheap and easy to implement. Of course the 'classical' roof tiles today, with bright white and wire stands, are products of Victorian materials that did not exist locally until the end of the 19th century.
Griff Rhys Jones and Trehilyn
The roof was dug into prominence in 2007, when the painter and architectural refiners Griff Rhys Jones began working at Trehilyn farmhouse in Llanwnda, Pembrokeshire. The building was in poor condition throughout and the rooftop grouting was pretty bad. Recovery involves the construction of a new roof which, in accordance with the previous roof, is stirred during construction.
As has been the theme of restoration construction in England for several years, a 'proper historical' lime plaster is used instead of Portland cement. The results of the restoration resulted in many bad comments. On the one hand, brilliant white roofs are newly criticized, although their vaginal discharge has always been an important feature of such a roof and will certainly subside with natural weathering. A sharper comment is to question whether a special chalk plaster is suitable for such a roof, raising the question of when they first appeared. The need to install completely on the new roof is questionable, it is likened to, "bringing a healthy child to a Victorian style show and breaking his legs to give a rickets appearance." Problems are also experienced during recovery and some mistakes to these are laid in various ways, by those who care and by outside observers, either on the quality of materials used or on plaster techniques.
See also
- roof later, hollow roof in Bermuda, used for rainwater collection.
References
Source of the article : Wikipedia
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