Random or Set Lengths? Problems, benefits, and everything else you need to know.

Before you read this article, you may like to read WHAT IS END MATCHED TIMBER? This will help you understand this article in more depth. CLICK HERE to read.

Please note that this article relates to the timber species Mortlock Timber offers as standard options and may not necessarily relate to all timber species.

Random Lengths

What are random lengths?
Random Length is the most common form of timber supply. Generally, it means that timber is supplied in a length spread from 0.9m – 3.9m with an average of 2.4m depending on the timber type. It is generally the most cost-effective way of procuring timber. Mortlock Timber works to a standard with random lengths, this standard means your timber will be supplied in length 0.9 – 3.9m and longer if possible, with 90% of the timber lengths being longer than 1.8m in length.

When installing random length timber, it means the following:
You will need to cut the boards back to land on a fixing batten or decking joist or your timber can be end matched and joined off a fixing batten (see diagram):

If you are using it as a T&G Cladding (Trendplank or Shou Sugi Ban) it is mostly supplied end matched (see: What is end matching?) which means you can join the boards off the fixing batten. If your timber cladding is end matched you will see this listed on your quote.
If you are using a click-in-batten system (Proplank) the battens can be end match and joined using Proplank joining clip. As not all Proplank projects are best suited to end matching Proplank is not supplied end matched as a standard option and is only supplied on request. If your Proplank battens are end matched you will see this listed on your quote.

WHAT IS END MATCHED TIMBER? Click here to find out.

Other names for random lengths: Mixed lengths.


  • Cost effective.
  • Less waste if end matched.
  • Shorter supply lead time for random lengths


  • More waste if not end matched, not all products are suited to end matching.
  • You will have joins, not everyone likes joins but some say it adds to the character of the project
  • Takes slightly longer to install.

Set Lengths

What are set lengths?
Set lengths means the timber is supplied in the lengths required for your project. Set lengths are mostly available between 0.9m and 3.6m. Set lengths are always supplied slightly over length to allow for onsite trimming.

Other names for set lengths: Specified Lengths, Cut lengths, Fixed Lengths.


  • Less waste on site
  • Less joins


  • Higher cost compared to random lengths.
  • Longer lead times

Why is timber supplied in random lengths as a standard option?

As timber is a natural product it comes with natural features like gum veins, knots, and surface checking. Because of this Mortlock Timber grades the timber to a Natural Select Grade which means the natural features are cut out of a board and the board length shortened. As its not known where natural features will appear until the timber is profiled and machine down to size so its difficult predict what lengths there will be in a finished pack of timber. If timber were supplied as set lengths to everyone this would produce a huge amount of waste timber.


Why does set length timber cost more?

Set length timber requires more labour, it means time sorting through packs of timber to pull out the lengths required for your project. It also means more waste for the supplier, if a board at the correct length is pulled out of a pack then its machined to size this may open a natural feature that needs grading out, once cut and the length is shortened it no longer meets the length requirement and becomes waste.

Whether you need set length or random length timber, Mortlock Timber can guide you through the process and recommend the correct option for your project.

Below are some projects where random length timber has been used:

Cradle - 4
Cradle Mountain Visitor Center – Random length end matched timber cladding
Iglu Student Housing Project – Random length timber batten feature wall
Timber Decking – Random Lengths

Below are some projects where set length timber has been used:

Scarborough Beach Redevelopment
Scarborough Beach SLSC – Set length timber supplied for timber façade.
Toyota Headquarters – Set length battens used as a feature wall.
Rosedale Residence – Set length Shou Sugi Ban Timber Batten Façade.