The Nature of Wood
In these days of plastic and mouldings it is sometimes easy to forget that wood is a natural material derived from trees. The corner summerhouses you will find at www.corner-summerhouses.co.uk are constructed of what is referred to as FSC timber, usually pine. FSC is an acronym for the Forest Stewardship Council, an independent international organisation formed in 1993 and dedicated to the responsible management of the world's timber resources. Wood which is FSC certified comes from properly managed resources and its use will not contribute to global deforestation.
Wood is an organic material comprised of fibrous cellulose layers. It is relatively easily worked and attractive to the eye and has been used in the construction of buildings and structures for thousands of years. It does however have one crucial weakness - when exposed to water it provides food for a number of wood rotting fungi which will over time weaken its structure and eventually cause collapse.
External timbers, such as those used in the construction of a corner summerhouse, are particularly prone to attack by these fungi which will eventually break down the woods cellular structure. Initially this will cause unsightly areas which will in time weaken and decay until nothing is left.
The effect of fungi attack can be reduced by the use of slow grown timber. The fibres of wood from this source tend to be more densely packed thus reducing moisture penetration and the attraction of the wood to undesirable fungi. In time however even slowly grown timber will succumb.
The most effective way to reduce damage by wood rotting fungi and to preserve the structure and appearance of your corner summerhouse is by treating the building with a suitable wood treatment.
Many corner summerhouses will come pre-treated, usually dipped in a water based preservative. This gives an initial degree of protection but a further preservative will normally require to be applied at the time of construction. To maintain the integrity and appearance of your summerhouse and to avoid weathering of the wood it is usually recommended that the building be treated with a preservative or stain at no less than three yearly intervals.
There are a wide range of treatments available, either water or spirit based. Some treatments are coloured and double up as a finish to the wood. Others are clear or have minimal colouring and can be applied prior to finishing with paint or a suitable woodstain.
Water Based Preservatives
As the name suggests the principal ingredient of a water based preservative is water to which a fungicide and perhaps a stain or other colouring will have been added. Water based preservatives have the advantage of low toxicity and ease of application. In general they will dry faster than spirit based preservers and brushes and other tools can be cleaned with water. Water based treatments also tend to be cheaper than their spirit based equivalents.
In general however they lack the penetrative capabilities of spirit based preservatives and may require more frequent application. In addition colouring of the wood may not be as effective.
Spirit Based Preservatives
In a spirit based wood preservative the main component will be an organic solvent such as white spirit or another petroleum based hydrocarbon. Although toxicity will be higher than a water based equivalent and brushes etc will require to be cleaned with a suitable brush cleaner, spirit based treatments generally penetrate the wood more effectively (important in close grained timber) and will provide longer lasting protection. As a result, in the longer run a spirit based option will probably work out cheaper than a water based preservative despite the greater initial cost.
Wood Stains and Other Finishes
Often a wood dye or stain will be incorporated in the preservative applied and there will be no need for the application of a further finish if colour is required. If you intend only to apply a preservative is is suggested that a coloured treatment is chosen and applied regularly to preserve the appearance of your corner summerhouse. A clear preservative alone, no matter how effective a banishing mould and fungi will not protect the appearance of your corner summerhouse from the effects of the weather and before long it will take on the grey, weathered appearance of old wood which has been exposed to the elements.
A suitable external wood stain or paint can be applied direct to the wood without treatment but we would suggest that a preservative, either clear or of a similar colour to the intended finish be applied first. It isn't possible to give general directions as to the method of application or time to allow between treatment and application of the final finish - for these you should refer closely to the instructions for both the preservative and the overcoat.