Frequently Asked Questions
T.C.R.S are the U.K leading specialists in Timber Crib Retaining Systems
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Timber Crib Retaining Systems – FAQ’s
What is a timber crib retaining system?
A timber crib retaining system is a cellular mass-gravity retaining wall.
The finished structure’s inherent weight and collective mass allows it to retain the target material without being destabilized.
It is constructed using individual sections of interlocking pressure treated timber to form a framework which is then filled with aggregate during assembly to add weight and stability to the structure.
Why choose a timber crib system over other retaining methods?
When compared to other mass gravity retaining systems such as gabions, timber crib offers a number of key advantages:
- Faster
- Durable
- More cost effective
- Minimal site disruption during construction
- More natural and aesthetically pleasing appearance
- Requires no specialist equipment or machinery to install
What is the life expectancy of a timber crib system?
Depending on the application required, (and therefore the preservative chemicals used) timber crib is treated with a minimum certified design life from 15 to 60+ years.
What Timber is used?
Pressure treated Radiata pine is used because of its inherent ability to absorb preservative to a greater cellular depth than most other materials thus increasing the service life of the structure.
What is used to in-fill the crib as it is being constructed?
Clean graded stone from 50mm
Can my contractors construct a timber crib system themselves?
Yes – though as with all structures of its kind, experienced specialists will build a timber crib faster than un-skilled labour.
Can you offer timber crib design and technical support?
Yes – a full range of site survey and technical support services are available nationwide.
What is your order/delivery lead time?
Typically 2 weeks
Will you supply timber crib components only?
Yes – though this is normally combined with our site survey and design service to ensure appropriate use and accurate estimated material requirements.
Can you service national contracts?
Yes – we operate throughout the U.K
Are your products and services certified and insured?
Yes – our in house team of qualified charted surveyors and structural engineers offer the protection of full professional indemnity.
Our materials are covered by industry approved certification for chemical treatment and timber source sustainability.
Our contractors carry appropriate health and safety accreditation and are fully insured.
How much does Timber Crib cost?
Simply get in touch with the approximate wall length and height and we will be happy to provide you with a detailed estimate of costs.
Can I install Timber Crib myself?
Yes – installing timber crib only requires a few simple tools and no special training or prior experience. Get in touch to learn more about our free tutorials.
How fast is timber crib to build compared with other retaining systems?
With a little practice even an inexperienced operative can achieve a frame build rate of 3.5m2 per hour.
This is roughly three times faster than an equivalent gabion wall and up to ten times faster than a concrete or masonry solution.
How high can a timber crib wall be built?
The maximum practical retained height of a timber crib wall is 12m
Can I build a curved timber crib wall?
Yes – see our curved timber crib wall section here
What angle are crib walls built at?
Crib walls repose at an angle of 1 in 4 – or, for every vertical meter the wall reposes by 250mm
Do timber crib walls have to be built on a concrete foundation?
In the majority of cases – yes. Please contact us for more details
How do I form the concrete foundation with the correct angle inbuilt?
We can supply a CNC cut, lost in cast foundation shuttering system which makes forming an accurate sub-base simple and fast.
How much concrete and infill stone will I need?
Contact us with wall length and height and we can provide accurate quantities for all materials required.
Can I fill a timber crib wall with soil or sand?
No – the only acceptable infill material is clean graded stone or suitable remediated recycled material such as a clean 6F2
Can I install plants into a timber crib wall?
Yes – we can supply planter bags that install within the wall to provide growing pockets for plants.
Contact us for details
How wide are timber crib walls?
Wall width depends on retained height. Broadly speaking the higher the wall, the wider it needs to be.
Contact us with your wall dimensions and we will be happy to give a detailed breakdown of all dimensions.
Is the timber you use responsibly sourced?
Yes – all our timber is sourced from sustainably managed PEFSC or FSC accredited forestry.
Will the timber you supply eventually rot?
No – provided the timber crib wall is installed correctly using appropriate materials, the structure will exceed the designed 60 year service life.
Do you recommend using a membrane at the back of the crib wall?
No – geotextile membranes can fill with particulates over time, causing a build up of moisture that lessens the material service life of the wall and increases the surcharge load and risk of failure.
I have a failed or damaged crib wall – do you offer a survey and assessment service?
Yes – we will be happy to inspect any pre-existing crib walls with a view of offering advice, a structural condition report and replacement costs.
Contact us for more information
Do timber crib walls meet local authority building control and highways standards?
Yes – Timber crib walls are fully compliant with Local Authority Highways and building control regulations in England, Wales and Scotland.
Can I build on top of a timber crib wall?
Under some circumstances – yes.
Contact us for more details.
Can I buy just materials and fixings from you?
Yes – we are happy to supply just materials and fixings direct to end users or contractors.
Can you provide design drawings and structural calculations for your crib walls?
Yes – though only in combination with the supply of materials
Do I need any special tools to construct a timber crib frame?
No – see here for a list of simple tools we recommend:
Power tools (Dewalt, Makita, Milwalkee or equivalent)
• 18v impact driver, 2 x batteries and charger
• 18v cordless electric drill
• 18v SDS cordless hammer drill
• 18v cordless circular saw
Hand tools (Stanley, Irwin, Bosch, Sandvik etc.)
• Torx T20 drive bits and holders
• String line
• Spirit level
• Folding builders square
• 13mm HSS or auger type drill – 130mm long
• 12mm SDS drill bit 200mm long
• Lump hammer
• White rubber mallet
• Hand saw
• Bevel gauge