Our top 10 Hints and tips if you are designing or building a roof which will be thatched.
There is plenty of information on the web about Thatch and thatch roofs but it is surprising how often, with a little more thought a thatched property can be made to look better and wear better.
1. Thatch works best on a steep pitch so water run-off is quick. A minimum pitch of 45 degrees is recommended in temperate climates such as in the UK, and Ireland and northern Europe.
· Thatch is also used for shade in warmer climates where the pitch is not so important because there is far less rainfall but these roofs will often leak in heavy rain.
· Thatch has an aesthetic appeal and a steep pitch also allows more of the thatch to be seen from the ground. Generally the thatch will look good if it occupies at least 50% of the buildings vertical outline when viewed from the ground.
· Inevitably even with a steep roof upper floor windows may often have a less steep pitch and may even impact on the cut of the ridge.
2. Thatch is surprisingly light despite its thickness and 33kgs per sq metre is a figure often quoted for a single coat of thatch.
3. It’s preferable that higher elevations of thatch do not shed water on to a lower one as this will quickly create a worn channel in the lower ones. Thatch porches look good when they are new but quickly deteriorate. Grey slate is a good alternative and will complement the colour of the thatch as it darkens down.
4. Windows which sit wholly or partially within the thatch look best if the thatch is as near as possible to the window
5. Although thatch is a very good insulator, additional insulation will need to be factored in when the total make-up of the roof from the outside to the inside is worked out.
6. If you are using insulation products and fire barriers, ensure they have been designed for thatch and are not just for general use. In the last 30 years there has been great progress in the availability and understanding of these products and Insurance companies look favourably on them. However there have been a few examples of condensation problems on new build thatch properties and renovated properties because builders have not adequately taken into account the drying out process and the correct use of vapour barriers and insulation. This whole subject needs careful thought. A good source of information is www.thatchingadvisoryservices.co.uk.
7. Contrary to popular belief both lead and mortar flashings can be used around chimneys and where thatch abuts walls. Consideration should be given to the type and age of the property and what materials the chimneys and walls have been built out of.
8. Also contrary to popular belief it is not solely the thickness of thatch that will be the main factor in determining how long a roof will last. Other equally important factors are the depth of fixings below the thatch, pitch of the roof, quality of the craftsmanship and materials and the roofs aspect and location.
9. Thatch is one of the most versatile of any roofing material and unlike more rigid materials that require lead and key junctures thatch will flow round most shapes. Here is an example:
10. Speak to a Thatcher at an early stage of your plans as he/she will be able to alert you to any design features that may work better if they were designed in a different way.