Panel types, surfaces
& technical characteristics

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Panel types

KLH® - CLT is offered in 3 standard qualities. Upon request special surfaces and panel build-ups are possible, depending on the availability of the required species and technical feasibility. Special structures are possible upon request.

By using double layers, the board’s longitudinal and transverse rigidity can be increased in a targeted manner. Changes to the board structure can be used to increase its fire resistance in order to meet special project requirements.

Maximum formatLength 16.50 m / Width 3.50 m / Thickness up to 320 mm
Minimum production length8.25 m - respectively in 5 cm increments up to the maximum length
Invoicing widths2.45, 2.50, 2.73, 2.95, 3.10, 3.20, 3.30, 3.40, 3.50 m

Typicaly, for the wall Covering layer in the transverse panel direction TT

Nominal thickness [mm]in Layers TypeLamella structure [mm]
KLH®90mm3sTT 303030
KLH®120mm3sTT 404040
KLH®160mm5sTT 4020402040

Typically, for floor and roof Covering layer in the longitudinal panel direction TL

Nominal thickness [mm]in Layers TypeLamella structure [mm]
KLH®90mm3sTL 303030
KLH®120mm3sTL 404040
KLH®160mm5sTL 4020402040
KLH®180mm5sTL 4030403040
KLH®160mm5ssTL 30+304030+30
KLH®180mm7sTL 20402020204020
KLH®220mm7sTL 30403020304030
KLH®180mm7ssTL 30+3020202030+30

Surface & Quality definition

As a standard, we produce KLH® - CLT in spruce and in three different surface qualities, which can be combined as required. This applies without restriction for all the panel types shown previously.

Surfaces treatment and special surfaces

Both the industrial visible quality and the domestic visible quality panels are fully sanded. Should you require UV protection, varnished elements or any other surface treatment, please contact us. The same applies to surfaces in other types of wood, which we can offer depending on customer requirements and the availability of raw materials.

Overview of the individual surfaces

Domestic Visible (DVQ)Industrial Visible (IVQ)Non Visible (NVQ)
Application AreaVisible components without restrictions used in residential constructions.Visible components with moderate restrictions, not recommendet for residential constructions.Pure structural components with subsequent panelling.
Demand towards Surfacehigh demandmedium demandno demand
Production-Related Referenceschamfer on TL panels (in the panel width joint)chamfer on TL panels (in the panel width joint)no chamfer
Surface Finishing In-Plantfully sanded (one- or double sided)fully sanded (one- or double sided) equalised (planed or sanded)
Surface Treatment In-Planton request on request protective coating on request, finishing not available

Minimum requirements


Criteria Domestic visible (DVQ) Industriel visible (IVQ) Non visible (NVQ)
Surface treatmentsandedsandedequalised (planed or sanded)
Type of woodone type of wood one type of wood;
spruce / fir (≤ 10 %)
are regarded as one
type of wood
addition of other types of wood possible
Colour and texture mostly balanced generally balanced no requirements
Blue and brown stains, red tinge slight discolouration
permissible (≤ 3 %)
slight discolouration
permissible (≤ 5 %)
no restrictions
tightly intergrown
permissiblepermissibleno restrictions
Branches, blackpermissible ≤ 25 mm Ø permissible ≤ 35 mm Øno restrictions
Loose knots, knot holespermissible ≤ 12 mm Ø permissible ≤ 15 mm Øno restrictions
Resin pocketssporadically permissible
≤ 3 x 50 mm
sporadically permissible
≤ 5 x 70 mm
no restrictions
Pithssporadically permissible
length ≤ 800 mm
sporadically permissible
length ≤ 1000 mm
no restrictions
Bark ingrowthimpermissible impermissible no restrictions
Waneimpermissible impermissible permissible
Compression wood sporadically permissible sporadically permissible no restrictions
Cut burrows from inactive
insect infestation
impermissible impermissible sporadically permissible
Wood moisture
during production
≤ 12 % ≤ 13 %≤ 14 %
Cracks and joints
(at a reference moisture
measurement of 12 %)
sporadically permissible
≤ 1,5 mm
sporadically permissible
≤ 2 mm
sporadically permissible
≤ 6 mm
Surface defectssporadically permissible
≤ 12 mm Ø
sporadically permissible
≤ 15 mm Ø
no restrictions
Surface re-treatment
(Filling and plugging of
branch holes, strips, etc.)
permissiblepermissible no restrictions
Defects on cutting edgessporadic small
defects permissible
sporadic defects
no restrictions
Cutting edge re-treatment
manually, using sand paper
Chamfer on DL panels (in the panel width joint)yesyesno
Range of validityThe given surface qualities valid:
- at the time of delivery
- only for the top layer, not for the edges
- for one-sided visible surfaces
- the edges and CNC-treated surfaces are subject to our NVQ surface criteria
- for double-sided visible surfaces, a small amount of on-site reworking is to be expected
Crack formationLike all solid wood products, the above stated qualities are subject to crack and joint formation as
a result of drying to their future compensation moisture balance when installed due to the product
characteristics. This cannot be prevented. Especially in the first few years, cracking noises can also occur alongside the formation of cracks, which can be classified as harmless.
Particularly in the case of surfaces in visible quality, make sure to avoid strong fluctuations in the room climate both during the construction phase (for example, when the screed is drying) and during the use phase. The ideal air humidity is between 40 - 60%.
Particularly with white glazed surfaces, there may be an undesired and irreversible contrast due to crack/gap formation. Please advise building owners and instruct all subsequent trades during the construction phase accordingly.
NoteWood is a natural product. Minor deviations from the table values are natural and are no reason for complaint.

KLH® Select Silver Fir Precious Wood Surface

KLH® Select Silver Fir (DVQTA)
Application areaPrecious wood surface for visible components in residential buildings, especially suitable for sophisticated architecture and largely knotless appearance
Demands on the surfaceHighest demands, ideally flawless and free of knots, balanced wood texture, very balanced, homogeneous appearance with colour tolerances that are typical of fir wood
Production­related referencesPanel thickness +5 mm (for one-sided, non-load-bearing top layer of silver fir), single
board width approx. 100 mm, single board length approx. 1 – 2 m, finger-jointed
Surface finishingFinely sanded over the entire surface (one side), surface re-treatment (knothole filling, strips, etc.) permitted
Surface treatment in-plantFinishing possible on request




Technical characteristics

Product name / BrandKLH® - CLT
OTHER PRODUCT NAMESCross-laminated timber (CLT) | X-Lam
APPLICATIONStructural elements for walls, floors and roofs
DURABILITYService classes 1 and 2 according to EN 1995-1-1
WOOD SPECIESSpruce (pine, fir, stone pine and other wood types on request)
PANEL BUILD UP3, 5, 7 or more layers depending on static requirements
LAMELLAEThickness 20 to 45 mm, technically dried, quality-sorted and finger-jointed
STRENGTH CLASSC 24 according to EN 338, maximum 10% C 16 permitted (compare ETA-06/0138)
ADHESIVEFormaldehyde-free PUR adhesive, approved for load-bearing and non-load-bearing components
indoors and outdoors according to EN 15425
WOOD MOISTURE CONTENT12% (+/- 2%) on delivery
MAXIMUM ELEMENT DIMENSIONSLength 16.50 m / width 3.50 m / thickness 0.50 m
INVOICING WIDTHS2.45 | 2.50 | 2.73 | 2.95 | 3.10 | 3.20 | 3.30 | 3.40 | 3.50 m
CUTTING TOLERANCESFor elements of a length and width > 1 m the tolerances are +/-2 mm, for standard panel types, standard trimming and a wood moisture content of 12%
SURFACE QUALITYNon-visible quality (NVQ) | Industrial visible quality (IVQ) | Domestic visible quality (DVQ)
Special surfaces on request
WEIGHT5.5 kN/m³ according to ÖNORM B 1991-1-1:2011 for structural analysis
Out-of-plane: 0.24% per 1% change in wood moisture content
MOISTURE MOVEMENTIn panel plane 0.02% per % change in wood moisture content, perpendicular to panel plane
(panel thickness direction)
0.24% per % change in wood moisture content
THERMAL CONDUCTIVITYλ = 0.12 W/(m*K) according to EN ISO 10456
HEAT STORAGE CAPACITYcp = 1600 J/(kg*K) according to EN ISO 10456
VAPOUR RESISTANCEµ = 300 (dry) to 46 (wet) according to EN ISO 12572
AIR TIGHTNESSKLH® - CLT can generally be used as airtight layers (Class 4 acc. to EN 12207).
Connections to other components, butt joints, penetrations, etc. must be sealed appropriately.
REACTION TO FIREEuro class D-s2, d0
RESISTANCE TO FIREFire analysis parameters acc. to ETA – 06/0138


Technical Approvals, Certificates and Eco-labels


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+44 (0) 20 3031 8070
General Business:
Project Enquiries:

KLH UK Limited
23 Jacob Street
London SE1 2BG

We really wanted to say thank you to everyone who has been involved in getting us this far. We have been really excited to see the structure go up and the on-site team have done an amazing job. The CLT looks great.

Mary & Klaus Morris | Blackwood House

I would like to record that I have been very impressed with your work on site and the efficiency of your construction team. The finished product is exactly as expected and was completed ahead of programme. Thank you for the efforts of your team.

David Spooner | Construction Project Manager | Hastings Pier Charity

Mayfield School are delighted with the new buildings. Innovative use of space and light in the atrium areas and other specialist classrooms will enhance the possibilities available to our staff and students.
The Sixth Form is designed not only to give a real feature (Heller-Up staircase), but is also a practical and useable large space which can be used by the whole school for various activities. The new building and external areas have created a real ‘WOW’ factor for our community as a whole.

Allison Greenwood | Deputy Headteacher | Mayfield School

The Mayfield School Project was delivered on time and within budget. It is to an excellent quality of workmanship which surpassed the expectations of the client team and the end user. The building’s design is rational, durable and above all maintainable which will ensure that Mayfield School will continue to provide teaching excellence within the London Borough of Redbridge.

Steve McConaghy | Senior Construction Project Manager| London Borough of Redbridge

I am the HT of a school in the UK which has been constructed using CLT. I am tremendously impressed with the very calm and purposeful learning environment that has been created. The students are so proud of the building and the exposed CLT is a major factor in this as it gives a high-end quality finish not common in schools in the UK. The CLT construction method enabled the building process to be rapid which was a major factor in us moving in on time.

Keir Smith | Head Teacher | William Perkin C of E School

We are completely delighted with the CLT!!! It’s been very exciting seeing our project in the factory and then going-up on site so quickly.
We love the exposed CLT walls and the character it gives the interiors – we can’t wait to move in. I think that the KLH team has been excellent throughout, from first contact, through the quotation stage to shop-drawings and the on-site erection crew – everyone has been very professional and helpful at all times. It has been a pleasure working with you all – I would be very happy to use KLH again in the future.

Ruth Butler | Ruth Butler Architects | Convent Lane

There is a great ambience in occupying a CLT school and it generates interest and a positive atmosphere with students, staff and visitors. Would definitely recommend it to another school.

Head Teacher | City Academy, Norwich

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