Timber Products: How to Avoid Post-Installation Issues

Timber Product Tips

I have written many articles for this publication over the past 20 years, usually about problems I have encountered after installation, often requiring expensive rectification.

Often, I have noted, it was not the fault of the timber product, but either an inappropriate timber was used or it involved poor installation practises.

Below is a brief comment on the problems and some suggestions on how to avoid post-installation issues when it comes to timber.

Timber Fit for Purpose

I have come across situations where the wrong timber product is used in certain situations. For example, an H3-treated pine post being used in-ground. H3 should be used in outside above-ground situations where it is exposed to only periodic moderate wetting.

I have formulated a comprehensive checklist that prompts questions, so the right product is used.

Installation Instructions

Incorrect spacing for decking is a common issue I see on site. For example, I often see 135×19 decking installed with only a 4mm gap between boards. This can result in the boards coming together in winter causing severe cupping.

Our recommended installation for this product suggests a 6mm to 7mm gap to avoid this issue.

Timber Flooring

In general, this timber product has a history of the most post-installation issues. That said, solid timber can experience moderate expansion and contraction. This natural timber movement reflects the humidity in its direct environment.

If we are engaged to install timber flooring, we undertake a thorough pre-installation inspection to ensure things like floor levels comply with regulations.

My advice for anyone having a timber floor installed is to engage an experienced flooring contractor and be assured by that contractor to return if any post-installation issues arise. If we supply a timber floor, we will issue suggested installation guidelines, so issues are minimised, as well as ongoing floor maintenance.

Timber Decking

Besides ventilation and errors in gapping, there are other common problems when installing timber decking. These are;

• Lack of Joist protection
• Wrong screw length
• Lack of regular maintenance

We strongly suggest the application of an oil base decking coating on all surfaces prior to installation, including the trimmed ends.

Bowens can supply pre-coating decking boards for 360-degree protection. If you are interested in pre-coating your decking boards, speak to our friendly staff in-store.

Timber Cladding and Weatherboards

Similar to decking, the stability of these timber products is essential. Here are some suggestions to help avoid postinstallation issues for timber cladding and weatherboards.

• Receive your cladding product with an oil-based pre-coat
• Ensure tongue and groove profiles allow for expansion in the winter months
• Apply a sealant for end-matched products
• Pre-paint Baltic weatherboards all round before installation. This avoids showing the undercoat if shrinkage occurs. Bowens can arrange this procedure.

Treated Pine Hazard Levels

Many mistakenly believe once timber is treated it will meet most situations. Accordingly, I’ve listed the various levels and uses:

• H2 protects from insect and termite attack
• H3 is suitable for above-ground outdoor use
• H4 is suitable for in-round use, but the product must be non-critical structurally eg; a pergola post
• H5 for in-ground critical structural use, eg; supporting a roof structure.

Installing ex 100x100mm Timber Posts In-Ground

I discuss installing ex 100x100mm timber posts in-ground because it is commonly purchased by our clients.

100x100mm Cypress Pine:

Natural heartwood is always more durable than natural sapwood. A user of this product should look at the ends to identify where there is more of the darker-coloured heartwood. That is the end that should go in the ground.

90x90mm Treated Pine:

With treated pine, the opposite occurs to the above. Why? Naturally, pine is not durable, that is why it is treated. However, the cell structure of the heartwood does not easily accept treatment whereas the cell structure of the sapwood will easily accept treatment.

By looking at the end grain I can identify the difference between the lighter-coloured heartwood to the darker-coloured sapwood (due to more penetration). The end with the darker colour should go in the ground.

Post and Beam Construction (Heavy Timbers)

Unseasoned timbers can commonly cause checks and end splits as the timber dries. An application of an oil/ sealer can minimise this issue. Unless a UV stabiliser or coloured stain is applied, it will not prevent the timber from greying off.

Always select a high-durability species such as class 1 or class 2 in-ground. This includes timber species like Ironbark or Spotted Gum. Recycled Timber is an (expensive) option, but because the timber could be up to 100 years old it will be seasoned resulting in a more stable product than the cheaper unseasoned.

Bowens is doing as much as possible so their clients can avoid expensive post installation issues, another reason for our claim to be The Builders Choice.

If you have any queries regarding timber products, do not hesitate to give me a call on 0412550740 for more information.

Jeff Harvey