- Project plans
- Project activities
- Legislation and standards
- Industry context
Last edited 04 Jul 2017
Technical drawing pen sizes
Technical drawing pens follow the same size-ratio principle as A series paper sizes, that is, an aspect ration of 1:√2, with the progression proceeding by folding the preceding size in two. When an A size piece of paper is folded in two it retains it's proportions.
This means for example that after drawing with a 0.35 mm pen on A3 paper and reducing it to A4, you can continue with the 0.25 mm pen. (ISO 9175-1).
 Find out more
 Related articles on Designing Buildings Wiki
Featured articles and news
Achieving air tightness in buildings.
What are the benefits of smart homes for Millennial end-users?
How dynamic briefing can result in an efficient project.
Achieving sustainable roads funding in England.
Your chance to comment on the draft BS 851188 - flood resistance products and flood protection products.
Rebuilding could take 20 to 40 years.
RSHP’s high-rise residential towers win a tall buildings award for excellence.
BSRIA study reveals strong growth in 2018.
Dame Judith Hackitt confirmed as keynote speaker – one year on from the Hackitt Report.
Save £100 on tickets.
Modern slavery in the construction sector.
What to bear in mind when claiming damages in construction.
How do we achieve sustainable clean-water infrastructure for all?