Square Posts > 125mm


  • Large stocks of posts
  • Pressure treated with preservative
  • 150mm, 175mm and 200mm sawn posts
  • Post anchors for 150mm posts
  • All 2.4 metre posts now PermaPost option 
  • Best practices for cutting and drilling
  • Careful post installation prolongs life


Product Details

At Southern Timber we carry a range of larger cross section tanalised posts up to 4.8 metres (approx. 16′) in stock. We can get larger cross sections and lengths cut to order. Smaller section (75mm and 100mm) sawn posts, and planed posts, are described elsewhere on the website.

Firstly, all of our posts are pressure treated and our standard products are pressure treated with Tanalith E preservative. This treatment gives the timber a light green tint which soon mellows to pale brown then grey, but most importantly provides protection against fungal and insect attack.  Because of durability issues we are selling more Permaposts with 15 Year Manufacturers Guarantee.  Therefore we are phasing out all standard tanalised posts at 2.4 metres and replacing them with Permaposts.

Square Posts – Cross Section Sizes Available

Both the 125mm and 150mm posts at 2.4 metres can be used for carrying pedestrian and medium diamond braced and field gates. Similarly the longer post lengths can be used for a wide variety of projects including pedestrian bridges, higher featheredge fence on unlevel ground, tree houses and for balconies.

Our 175mm x 175mm and 200mm x 200mm posts have always been used as gate posts but we have been increasingly asked for longer lengths of these posts. The 200mm x 200mm posts are stocked at 3.6 metres and 4.8 metres and some of the local timber merchants and civil engineers purchase these from us.

125mm x 125mm, tanalised at 2.4 metres (approx. 8′)
125mm x 125mm, tanalised at 3.6 metres (approx. 12′)

150mm x 150mm, tanalised at 2.4 metres (approx. 8′)
150mm x 150mm, tanalised at 3.6 metres (approx. 12′)
150mm x 150mm, tanalised at 4.8 metres (approx. 16′)

175mm x 175mm, tanalised at 2.4 metres (approx. 8′)

200mm x 200mm, tanalised at 2.4 metres (approx. 8′)
200mm x 200mm, tanalised at 3.6 metres (approx. 12′)
200mm x 200mm, tanalised at 4.8 metres (approx. 16′)

Other square post options at Southern Timber

We also carry a number of 75mm and 100mm planed redwood posts. These are available in 75mm x 75mm at 2.4 metres and 3.6 metre lengths. However our 100mm x 100mm sections are a generous 94mm after machining and treatment and they are normally available at 3.6 metre and 4.8 metre lengths. Therefore these are ideal for elevated decks, first floor balconies and other projects where large posts with a planed finish are required.

Best Practices – Square Tanalised Posts

The last few winters have been exceptionally wet and this has impacted on the service life of many posts. Following the best Practices of the Timber Trade Federation will help, but we strongly recommend you consider our 15 year Guarantee Posts

However if you do cross cut your tanalised posts for any reason you must ensure that the factory treated end is put in the ground, never the cut end.

Any cross cut post ends should always remain above ground, cut at an angle and exposed surfaces to be brush treated in accordance with preservative manufacturer’s recommendations and wherever possible use post caps.

Finally, ensure water can drain away from the foot of the post, especially when they are set in concrete. Failure to do so will mean the post stays wet for long periods increasing the risk of decay.

Phone to order

01803 813 803

Lines open 7:30 - 17:00 Mon - Fri

Delivery details

Usually within 1-2 working days

At Southern Timber we offer a kerbside delivery through the Torbay, Teignbridge, Exeter, South Hams and Plymouth areas. While most deliveries are free sometimes they may be chargeable depending on location and the total value of the order.

We offer next day delivery, when required, for our normal delivery days (Monday to Friday) and areas. Customers are requested to phone in before 12.00pm on the day prior to delivery with their complete product listing, delivery address and payment details.