When you take delivery of your wooden playhouse it is unlikely it will have had a final finish applied. The vast majority of wooden playhouses delivered for home assembly will have been either dip or pressure treated in a water based preservative and the purchaser will be responsible for applying the final decorative and/or protective coat.
The application of such a finishing coat and its subsequent maintenance is important from the point of view of prolonging the life and preserving the appearance of the playhouse and it is also likely to be a condition of any manufacturer's warranty.
A water based dip treatment will deter rot and insects attacking the wood for a time, but usually not for much longer than it takes to finish the manufacturing process and deliver the playhouse. A dip treatment, as the name suggests, involves simply dipping the components of the building in the preservative and the result is a protective basecoat on the surface of the wood. Pressure treatment is more effective in that the preservative is applied under pressure and should penetrate deeper than the surface. This may be sufficient to protect the wood from rot or insect damage for a few years.
Whether the playhouse is supplied dip or pressure treated we would recommend the application of a final finish just prior to assembly or immediately following delivery if it looks as if assembly might be delayed. If this is not done the wood will soon take on a grey weathered appearance which makes finishes difficult to apply and reduces their effectiveness and longevity.
Decorative and Protective Treatments
When it comes to applying further treatments there are a number of options. It is unlikely that the pre delivery treatment will have sealed the surface of the wood so you will have the option of applying a further water or solvent based preservative. This should not be necessary if the playhouse has been pressure treated but if only a dip treatment has been applied and you have the time it's certainly worth considering the application of a further preservative before applying any decorative finish.
You will have the choice of either a water or spirit based preservative. We would recommend the application of a spirit based preservative to the exterior surfaces of the building and you may find that this is a requirement before any manufacturer's guarantee will apply. Spirit based preservatives are more effective and longer lasting than their water based equivalents and are available as both clear and coloured treatments. If you also intend to paint your wooden playhouse in bright and happy colours, apply a clear preservative and be sure to check that the wood can be painted after treatment. This will be possible with most commonly available treatments.
Many coloured timber treatments are available, mainly designed for sheds, fences and garden furniture. These are generally suitable for the treatment and decoration of wooden playhouses although they are often water based and will probably require more frequent re-application than a high quality exterior paint finish - annually is usually recommended.
Such coloured treatments are however usually quick and straightforward to apply but remember to check that the treatment you choose is not intended for use on rough sawn timber only. To comply with safety regulations your wooden playhouse will be planed to a smooth finish. If you choose a treatment intended for rough finished wood it's unlikely that the colour will apply evenly and the preservative benefit will be short lived.
If you intend to paint your wooden summerhouse, and a high quality paint finish usually gives the nicest appearance combined with durability, an exterior timber paint "system" is what you are looking for. This will usually consist of an undercoat followed by the application of either one or two gloss or satin top coats. A gloss topcoat will give the classic shiny finish while a satin paint with give more of a soft sheen to the surface of the wood.
Be sure to check that the undercoat you apply is correct for the colour of the final finish. Usually a particular colour of undercoat will be specified for use with the top coat you are applying. Modern water based exterior paints are far more durable than their predecessors so don't be too concerned about applying a water based finish. This has the advantage of reducing fumes and making tools easier to clean as water rather than white spirit can be used. Older children might even get involved in the painting process!
To ensure a high quality finish the areas painted should be sanded smooth with fine sandpaper following application of the undercoat. Although the playhouse will be smooth to begin with it will be slightly roughened following the application of the initial coat of paint and sanding at this stage will ensure a smooth finish.
An exterior woodstain will give a durable and attractive finish to your wooden playhouse. Typically available in a variety of wood finishes, you will find both quick drying and and longer lasting, slower drying stains readily available. Woodstains can usually be applied directly to the bare wood. Two to three coats will be necessary and as in the case of painting, the wood should be lightly sanded following application of the first coat.
Don't Delay !
Although it is quite understandable that you (and your children!) will want to see your new wooden playhouse erected as soon as possible, please take the time to carry out the vital task of applying the final decorative/protective coat. If left until after the playhouse is in use it can all too easily become one of these jobs on the list that never gets done.
We would recommend that whatever finish you choose, it be applied to the individual component parts of the playhouse prior to assembly. That way there is less likelihood of missing exposed parts and the job will in fact probably be easier. It's also easier to keep the kids away from parts of a wooden playhouse on which paint is drying than an assembled playhouse - especially if it's a brand new attraction!
Remember - you will only need to apply the finish to the exterior parts of the playhouse. The interior can be left in the natural wood although if you do wish to decorate internally, interior wood paint can be used. If you intend to decorate the inside of the playhouse we would recommend the use of an interior paint which is EN71 compliant, or at least water based.
Once the job is done all that there is left to do is to enjoy your wooden playhouse. Properly finished and maintained, a wooden playhouse will last for years and provide the children with many happy and memorable days of outdoor play.