Are H5 laminated posts certified for in ground use?
Yes. Prolam is leading the way with H5 laminated structural in-ground posts.
Codemarked for NZBC Compliance in B1 and B2, it means you can use Prolam in-ground posts with more confidence than ever.
What is the tributary joist & bearer span?
The tributary area is a loaded area that contributes to the load on the member supporting that area. On the Prolam Specifier under each non-bracing calculator, the diagram shows how to calculate this.
Do I have to seal the portion of post that goes in ground?
When using the posts in-ground, the portion of the post that is to be in-ground must be sealed with a moisture-resistant coating prior to installation.
This can be sealed with the same paint or stain as the above-ground portion of the post.
What do I have to seal the in-ground portion with?
Typically the same sealer is used.
Can I use H5 posts in-ground for structural use?
Yes. Prolam posts are 'Codemark' certified for inground structural use.
Where is the bracing posts chart on the Specifier?
Under http://specifier.prolamnz.com/resources refer to the document 'Prolam Bracing Posts'
Should I go by absolute deflection or residual deflection?
Depending on the allowance for deflection below the horizontal line, the residual deflection is long term deflection below horizontal after pre-camber and is the recommended value for typical designs. The 'absolute deflection' is the maximum beam movement. After selecting 'calculate' these notes are located below the list of products that suit the design.
How do I know if my verandah/carport roof or deck requires bracing?
Free-standing carports and decks as well as attached verandah/carport roofs and decks projecting more than 2m from the building, require bracing.
Why should I use Prolam Glulam instead of steel
Here are just a few reasons:
- Easier and lighter to handle and fix
- Friendlier on the environment - stores carbon rather than emitting it
- Uses NZ’s only renewable construction material - plantation timber
- Uses 14 times less energy to produce than equivalent steel beam
- Superior Fire Resistance compared to steel
- Lower maintenance - Glulam does not rust or corrode
- Cost effective - No boxing in or covering as with steel beams
- Appearance - natural warmth and beauty of timber cannot be reproduced in steel
- Will not buckle or distort in response to temperature changes
- Direct fixing of plates, joists and other connections is much easier.
View our brochure on the benefits of building with wood here.
Why should I use Prolam Glulam instead of solid timber?
Because Prolam Glulam is manufactured from selected grade, kiln-dried material it is more stable than a sawn timber beam of the same section. The tendency of large section sawn timber to twist, split and shrink is greatly minimised in Prolam. A Prolam beam can reduce the overall section of members up to 40% compared to unseasoned timber, as they are pretensioned.
View our related FAQ video here.
Are there any visual differences between PL8 & PL12?
Both PL8 and PL12 have the same visual appearance and can be identified by the colours painted on the end of the beam.
What colour are H3.2 Prolam beams?
H3.2 is typically known to add a green tinge to timber, however as Prolam is machined after treatment this brings up the colour to a light brown.
What is the difference between PL8 and PL12?
PL12 has higher strength and stiffness properties and enables you to achieve bigger spans with larger loaded dimensions.
For a similar span and loaded dimension, a PL12 can offer a smaller section where the space is limited or aesthetics are important.
Are glulam beams stronger than standard timber beams?
Prolam Glulam beams are stronger than standard timber meaning greater spanning ability.
View our related FAQ video here.
Can I substitute SG8 for PL8?
Yes. SG8 timber may be directly substituted with equivalent size PL8 PROLAM.
The strength and stiffness of glue laminated timber manufactured to AS/NZS1328
with a stress grade PL8 will exceed or equal that of grade SG8 timber.
What finish should I ask for on my beams?
If your beam is going to be used in a situation where appearance is important such as house interiors, halls etc - Visual Appearance Grade A should be specified. If you require a sanded finish, please specify. Non visual grade is intended for use where the product is not seen and occasional chips and voids are acceptable.
What is the fire rating of Prolam?
The BRANZ appraisal states a charring rate from the table below.
Charring Rate (mm/min)
It is recommended that this simplified table of data derived from "White's" model and should be adopted for design of fire resistant timber structures in New Zealand. Prolam density is 550 kg/m3.
How far can a glulam beam span?
This can depend on a number of factors such as roof weight, wind zone, roof pitch etc. This can easily be calculated using the Prolam Specifier https://www.prolamnz.com/the-prolam-specifier-specify-with-certainty/ or Prolam span tables.
How much does the Prolam product weigh?
The weight of Prolam PL8 & PL12 treated to H1.2, H3.2 or H5 is around 550 kg's per cube. For example, the weight of a 240x88 H3.2 PL8 4.8m is around 56 kg. E.g. 0.240 x 0.088 x 4.8 x 550 = 55.76 kg.
What strength grades should Glulam be designed to?
The Glulam standard, AS/NZS 1328 states grades from GL8 to GL12, Prowood is certified to produce PL8 and PL12 grades.
Click here to view our video on the difference between PL8 and PL12.
Do you have Design Timber Properties ?
Yes these are available on Prolam website which can be found by searching "design properties" and in the Prolam structural timber guide.
Why have PL17 been discontinued?
Prolam doesn’t manufacture any products with the structural grade of PL17 anymore due to that particular feedstock being unavailable.
See related FAQ video here.
What is the difference between LVL and Prolam/Glulam?
LVL (Laminated veneer lumber) refers to a manufactured timber product made from thin veneers (normally 2-3mm) glued together to form a beam. Prolam is a glulam product which is made from thicker sections of timber, generally 30-45mm thick, glued together to make a post or a beam.
Will CCA treated Prolam cause corrosion on galvanised fixings?
While this may be a problem with solid unseasoned timber, Prolam does not act in the same way. Because all Prolam is manufactured from material which is kiln dried after treatment, the treatment salts are thoroughly fixed into the timber. They will therefore not subsequently leach out or affect galvanized fixings.
For additional protection it is recommended that bolts be greased before inserting into CCA treated Prolam beams that are exposed to the weather.
Can I buy direct from Prolam?
All Prolam products are supplied through the main timber merchants nationwide as well as many timber specialists stores.
Click here to view our store locator.
How long should I keep the wrapping on?
Wrapping of Prolam beams is primarily to protect them from marking during handling and transport. This is not designed to be a waterproof protection. Once on-site water can often get in under the wrapping and cannot get out. Wrapping should be slit to provide drainage. Wrapping can be left on Prolam beams for as long as possible (even during construction) to protect against accidental marking. Also be aware that partial removal of wrapping to access connections may cause patches of discolouration by exposure to weather.
Do we provide pricing?
Yes, we do. We supply pricing and product through the timber merchants. If you're a builder, let us know your preferred merchant and trade account name, and we'll take care of getting you a quote for the Prolam you're after.
Do I need special connections for my beams?
Prolam can be treated as natural solid timber when it comes to fixings. The use of standard nailing systems and bolts is normal. In exposed situations dark stains can appear from the use of unprotected steel brackets and bolts. Use galvanised metalwork where there is any possibility of moisture.
Where can I find the design properties of your beams?
Design properties are in the Prolam structural timber guide and can be found by searching "structural properties" on our website.
Can finished Prolam beams be re-cut and drilled?
Any cutting, drilling or slotting that exposes unsealed timber must be protected with an application of appropriate weather or treatment sealer. Avoid cutouts, rebating or drilling in the top and bottom edges of Prolam beams. These could cause serious weakness in tension and compression areas. Consult the manufacturer or designer first.
Do you have substitutions for Hyspan?
Yes. Click Here to download our comparison chart.
Do splits along glue lines mean delamination has occurred?
Actual delamination is a failure in the laminating process. While an opening along a glue line may be indicative of delamination there are other more common causes. Typical checking that occurs in large section timber in response to moisture variation will most naturally occur in Prolam along a glue line where the natural continuation of the timber fibres is interrupted. This is often mistaken for delamination.
How dark can I paint my beams?
Prolam mustn't painted with any colours with a LRV rating of 45% or less to avoid risk of cracking and distortion of the timber.
What type of quality assurance comes with Prolam Glulam Beams?
All Prolam Glulam is manufactured to comply with the Australia and New Zealand Standard AS/NZS1328 and AS5096 - Glue Laminated Structural Timber A.
How serious are checks and why do the appear?
Surface checking and splits occur as timber is allowed to absorb moisture then dries out in response to environmental changes. Surface fibres are more severely exposed to these changes than the inner core and as a result of the movement in these fibres as they dry and shrink, surface splits may occur. Changes in atmospheric conditions will affect the appearance and disappearance of these checks. The effect of surface checks are superficial only and do not usually have any effect on the structural performance of the Prolam.
Can Prolam Glulam beams be used in exterior situations?
Yes. Treatment to hazard class 3 (H3.2 or H5) is recommended for all Prolam beams exposed to the weather. Along with this treatment an exterior adhesive resorcinol is used. The finished beams must be suitably coated with either a penetrating sealer or film-forming coating. When painting or staining external Prolam Glulam beams it is preferable to use lighter colours. Dark colours attract heat and may cause surface shrinkage. Because Prolam Glulam is chemically inert it is ideal for corrosive atmospheres such as swimming pools, marine structures, fertilisers and scouring plants where steel is subject to rust and corrosion.
View our related FAQ video here.
How can these checks be minimised?
Prolam beams are provided with a sealer coating if requested, which controls the ingress of moisture into the timber, and is done before the beams leave the factory. If the beams are exposed to the weather for a greater period than 8-10 weeks a further coating should be applied.
Consult our painting instructions for permanent sealing requirement.s
Where can H1.2 treatment be used?
Prolam treated to H1.2 is only suitable to be used in the building envelope as NZS3604.
What is the classification of timber to be used for joint design as per table 4.1 of NZS3603?
The classification for Prolam products would be J5.
What is the difference between Visual and Non-Visual grades?
Prolam Visual is made from visually selected sharts that are then finger jointed together into a long length and laminated into the required beam. This grade is recommended for use in highly visual areas and when a paint or stain quality finish is required.
Prolam Non-Visual is made up from stress graded timber and is not visually graded. The non-visual grade is recommended where the beams are not seen.
View our related FAQ video here.
What is the difference between GL and PL grade?
The Gl prefix is a reference to the old term 'Glulam', where the PL is the prefix for branded 'Prolam" structural timber.
Why is bandsawn finished smaller than standard?
Bandsawn finished Prolam posts and beams are 6mm smaller than standard, because we have to cut the bandsawn finish into the beams after they are made. Use the Prolam Online Calculator to specify this product.
Can you cut drill, machine Prolam after manufacturing?
Yes, because Prolam is pretreated before laminating, all pieces are fully treated, so any cutting etc. does not need apaint on treatment applied to the cut portion. However any cuts can be sealed.