Frequently asked questions about log chinking (sealing) with sealant GULBUVE
It is good to chink log or wooden buildings immediately after construction?
Wooden buildings are often built from insufficiently dried timber and therefore they will continue to dry and settle for next few years. Therefore we recommend to seal wooden buildings’ seams in at least 2 years (depending on the condition of the logs and environmental conditions). Sealant is very flexible and it can compensate seams’ deformation (move together with timber and expand) also in case if logs slips one from another or warps in edges.Practically the same happens also in wooden frame buildings built from beams. If there is no possibility to wait with the usage of sealant for log buildings, you can seal the seams immediately and repair cracks after few years if necessary.
If construction is done using dry wood (dried logs or beams), seams between logs can be sealed/ insulated immediately after finishing the construction works. Seams sealing in-between the logs is recommended to perform before processing surface with any type of coatings. Prior priming of seams surface with linseed oil primer GULBUVE is necessary only in case if the sealant is used for processing well absorbent wood.
Why is it necessary to seal cracks in logs or gaps between them?
There are many reasons why it is necessary to use a sealant when insulating wooden buildings.Sealing the seams and cracks of log houses or wooden buildings improves their thermal insulation features, protects beams and logs from moisture (rain, snow) as well as inhibits favoured development and living places of insects damaging the wood. Proper usage of the sealant prolongs the lifetime of the building, saves energy (improves thermal insulation) and prevents problems due to the timber damaged by the insects.
Is it necessary to use seam backing – wool, linen, sealing materials or ropes?
Seam backing rod ensures the necessary filling of big cracks and seams as well as proper preparing of seams treatment with the sealant.It is desirable that sealant is fixed only in two seams/ cracks places and their middle part can freely expand and compensate the deformation. The fulfilment of this necessary condition is ensured with the help of flexible seam backing material (for example, sheep wool) that sealant is not sticking to, but can freely move around it. Another advantage of using seam backing rod is diminishing the consumption of the sealant in that way ensuring economy of materials and finance.
Thus; seam backing material itself (e.g. sheep wool or linen rope) cannot replace the sealant. It is necessary to follow a correct thickness of sealant layer put on the seam filling material. The thickness of sealant layer depends on the total height and depth of seam or joint.
Often mistake – too thin sealant layer on sealable material (backing rod) that after drying repeats the outline/shape of material used for backing of seam and respectively causing cracks. Sealing material is not a must in places where the width of seams, cracks or joints does not exceed 1cm. Only sealant can be used for sealing such seams.
Is it better to chink (use mastic) before or after painting the building?
Prior to processing wood with any of wood painting or saturating agents it is better to apply sealant directly on wood. Exception – highly absorbent wood, it is necessary to prime beforehand with linseed oil primer GULBUVE.In practice it’s not always possible to ensure the surface of unprocessed seams since the biggest part of buildings surface is already coated with specific substances, agents or colours (for example on the base of linseed oil). Therefore; we offer recommendations that will help to determine if the surface is suitable for coating of sealant for log buildings:
- If wood surface is coated with antiseptics or wood protection means (STAFOREST, STAFEKS, LOG GUARD etc.) it keeps its hygroscopicity and is suitable for applying sealant for wood. Exception is antiseptics that create film on the wood.
- If wood surface is covered with natural oils or linseed oil colours (linseed oil paint-stain NATURA), that absorbs into the wood and doesn’t create a film on it, they doesn’t influence sealants applying into the seam or crack. If application of the materials mentioned is planned, it’s recommended to apply the sealant before they are used.
- We don’t recommend to use the sealant on the wood that is covered with wax or lacquer or similar materials (for example, colours containing alkyd or acrylates), that create a film on wood surface and doesn’t allow direct contact between sealant and wood surface.
- In order to make sure that the surface of the seam is suitable, we recommend to firstly make a test by applying sealant to one crack or seam and in 3 weeks separate it from the wood. If the sealant together with a coating film is easy to remove from wood, seam place is necessary to purify till pure wood surface.
- Not recommended to apply the sealant on other mastics or putty that are poorly secured in cracks or partially secede from wood surface. In such cases cracks are necessary to purify from the old mastic and putty.
An important factor is the age of the building, degree of building’s drying and settling. The smaller diameter of logs or beams, the smaller height of sealant’s seam is necessary. For buildings with the average diameter of logs is 25 to 30 cm, the recommended height of the seam is up to 2,5cm. The height of the sealing seam depends on the depth of the seam. The optimal seam depth of the sealant’s layer is approximately one third from its height.
What is best width of seam/ joint?
The optimal width of the seam place depends on the condition of the seam or crack, diameter of the beams or logs used and other factors.
An important factor is the age of the building, degree of building’s drying and settling. The smaller diameter of logs or beams, the smaller height of sealant’s seam is necessary. For buildings with the average diameter of logs is 25 to 30 cm, the recommended height of the seam is up to 2,5cm. The height of the sealing seam depends on the depth of the seam. The optimal seam depth of the sealant’s layer is approximately one third from its height.
Which sealant colour to choose?
Sealant for log buildings GULBUVE is offered in the most demanded shades. If necessary the shade of the sealant can be adjusted using linseed oil colour NATURA. More common shades of the sealant – corresponding the gamma of logs colour, just 1-2 tones darker.What weather conditions are best for chinking?
Before applying mastic we recommend to get acquainted with the weather forecast for the upcoming days. Suitable temperature for sealing log buildings should not be less than +5°C.Factors effecting mastic drying – weather temperature and moisture, wind and surface ability to absorb moisture, the height and depth of the seam, the method of applying the sealant.
After applying the sealant it’s necessary to protect it for few hours from direct influence of the rain and the sun that can cause too rapid water evaporation from the thin sealant’s layers as well as small cracks can occur. Under normal conditions the sealant creates water resistant surface film within 4-6 hours, dries out completely within 24 hours. Mastic shouldn’t be exposed to the temperatures less than 0°C for at least a week. Final sealant’s features in its whole volume are gained in approximately 1-3 months from the moment of applying.