How the substrate affects external timber doors
When external timber doors have been selected, it is important to note that they contain a number of substrate features that could affect their performance, either now or in the future. This article takes a closer look at some of these features and the affects they can have. Sometimes, simply painting or staining doors can help prevent any issues from occurring:
- Density – The heavier and more dense the species selected, the less prone it will be to absorbing moisture. The lighter the species, the more prone it will be to taking on moisture.
- Edges – The presence of sharp areas can create stress in paint films, eventually causing them to fail. Arrised or rounded edges permit film movement with minimal stress.
- Unseasoned (Green) – The use of timber that is “green” increases the likelihood of blistering and peeling in the paint. A stain will generally be more effective.
- Weathered vs unweathered – External timber doors that have been exposed to weathering prior to being finished often experience poor paint adhesion, but stains don’t tend to be affected.
- Heartwood vs Sapwood – Heartwood has better staining potential than sapwood, but both are quite suitable for being painted.
- Smooth vs coarse – Surfaces with a smooth texture are able to hold paint better than those that are coarse. Surfaces with a coarse texture, however, will provide a better performance.
- Gum pockets – The presence of gum pockets in the door can lead to resin exudation, unless they have been pre-treated and sealed. This is important for maintaining the appearance.
- Knots – The presence of knots in the timber can lead to premature cracking, staining and resin exudation. These occurrences can be avoided using knotting varnish or on manufacturer’s advice.
- Bark – If any pieces of bark, no matter how small, are allowed to remain on the door it could lead to the premature failure of any coating (including both paint and stains).
- Insect damage – Sometimes insect damage cannot be avoided. The damage must be treated or filled before finishing to avoid failure.
- Moisture range – The normal range is between 10 and 15%. Levels that are higher can be very detrimental, particularly if a solvent borne finish is used (where moisture vapour permeability is low).
[edit] Find out more
[edit] Related articles on Designing Buildings Wiki
Featured articles and news
Tasked with locating groups of 10,000 homes with opportunity.
Open inquiry into the remediation of dangerous cladding
The committee wants to hear views in its call for evidence.
CLC voices concern over the practice of amending industry-approved forms of contract
The need to address PII issues, tackling accountability, competence and better information management.
Delivering radical reform in the UK energy market
What are the benefits, barriers and underlying principles.
Information Management Initiative IMI
Building sector-transforming capabilities in emerging technologies.
Recent study of UK households reveals chilling home truths
Poor insulation, EPC knowledge and lack of understanding as to what retrofit might offer.
Embodied Carbon in the Built Environment
Overview, regulations, detail calculations and much more.
Why the construction sector must embrace workplace mental health support
Let’s talk; more importantly now, than ever.
Refurbishment for net zero; the BSRIA white paper
The everyday practice of tackling energy efficiency, fabric first, ventilation, air quality, and occupant wellbeing.
Sustainable construction design teams survey
Shaping the Future of Sustainable Design: Your Voice Matters.
Ensuring the trustworthiness of AI systems
A key growth area, including impacts for construction.
Foundations for the Future: A new model for social housing
To create a social housing pipeline, that reduces the need for continuous government funding.
Mutual Investment Models or MIMs
PPP or PFI, enhanced for public interest by the Welsh Government.
Stress Awareness Week ends but employer legal duties continue.
A call to follow the five Rs for the business and for the staff.
Key points and relevance to construction of meeting, due to reconvene.
Cladding remediation programmes, transparency and target date.
National Audit Office issue report on cladding remediation.
HBPT and BEAMS Jubilees. Book review.