Arbour Seat

The arbour seat — or “sentry box” as our family has come to call it — was one of the first features I designed and built in our garden. That was back in 2008. At that time the area of the garden it was located in was only just taking shape and was used for vegetable growing. A few raised beds had been cut into the rough lawn creating a series of grass paths. The beds were laid out in a formal arrangement around a large central bed at ground level as you can see in this photo:

Arbour seat (left) in vegetable garden (2009)


The arbour was placed so that it looked across the garden along one of the two main axes of symmetry. Over the years, the garden around the arbour developed considerably, with the addition of paving, a pond and most recently, with a repurposing of the area as a Mediterranean Pond Garden.

These photos show the arbour at different times during the garden development. (1) 2010 photo shows the arbour positioned at the end of a short vista across our simple vegetable garden. (2) 2014 we replaced the grass paths with brick paving and replaced the central bed with a pond and bridge. (3) Later, in 2017, the pond was renovated with brick edging. (4) In 2020/21 the fence was renovated, and the arbour rebuilt, giving it a new rot-proof Accoya base and concrete footings. At this time the old oak raised beds were replaced with Accoya and the vegetable garden turned into a perennial mediterranean-style planting.

Role as a Design Element

One of the main design functions of the arbour is to provide a focal point for the surrounding planting and paths. By placing it at the end of a short vista across the pond, the eye is drawn to it, producing a sense of purpose and harmony in the layout. When sitting in the arbour seat one looks back across the pond towards the adjacent dining area. It also breaks up what would otherwise be a long run of fence, creating a natural stopping place for the eye and feet, as well as a destination for visitors.

Arbour Seat

The Arbour Seat is situated along the short axis of symmetry of this part of the garden. The long axis is terminated with a bench and hedge ‘window’. Simple features such as these produce meaningful ‘places’ within the garden.


Apart from being a lovely place to sit and admire the garden, or shelter from a light shower, the Arbour is handy as a convenient store for garden tools. In fact it contains a little shelf with pegs beneath so that garden chemicals can be stored out of sight while the trowel and dibber hang ready to use. The area in front of the arbour is wide enough to place a small table and chairs, which along with the arbour bench can easily sit 3 or 4 for tea or lunch.

Design & Construction

In some ways this mini-shed has been constructed “inside out” with the framework (black) being on the outside, while the cladding (golden-brown) is on the inside. Aesthetically, this gives this building a lot of character, and prevents it looking like the typical nondescript box shed. The problem with such a design is that the framework is exposed to the elements and prone to rotting. Normally, cladding protects the structural timbers.

I was aware of this issue when designing the arbour, so aimed to mitigate these issues by using pressure-treated timber and a quality external microporous stain. After ten years, however, rot did get in to the base of the vertical posts where they sat on horizontal timbers, leading to a rebuild in 2021 (see below). It didn’t help that the original base on which the arbour sat was nothing more than some 2×4 treated timber (see above left) which was not even specified for ground-contact. Rot got into these pretty quickly, so it was no surprise that it eventually found its way into the end of the vertical posts. If I was building this again, I would have sat it on a brick-base or on rot-proof accoya.

For the framework I used 2″x3″ PAR timber (i.e. 50mm x 75mm, planed all round to give a finished size of 44mm x 69mm). I had it pressure treated before delivery. I rebated the back edge of each of the framing pieces so that the cladding could be fitted flush, screwed from the inside. The external corner timbers were slightly larger (3″x3″ PAR, 69x69mm finished) as they needed to be rebated to take cladding in two directions.

The roof was tiled with cedar shingles, nailed to tile battens, which remain in good order a decade later.

I no longer have the original plans, but like most of my garden buildings, I always start with a precise scale diagram, usually drawn up on the computer (I use MS Word with a 1mm grid). The purpose of such a drawing is th help me think through the exact build process, especially the joints between timbers. As I draw I am visualising the construction technique step-by-step. Once I have a complete diagram I can calculate timber dimensions and lengths and order the correct amount with minimal wastage.

Plan showing arrangement of rebated structural timbers and inset shiplap panels plus rear fixing to fence post. (not to scale)

Most of the joints are simple butt-joints, screwed and glued. The framework only really became stiff and strong once the ship-lap boards were screwed in place.

Despite it being the smallest of my garden buildings, the sentry box is surprisingly heavy. Once constructed, it needed two of us to move it into place.

It has a vertical timber (2×4 inch) running down the centre of the back panel, screwed through from the inside which helps give the long ship-lap across the back some additional rigidity, but also butts up against the fence post which is immediately behind it. The whole arbour was then attached to the fence post using a large 5 inch long hex-screw which was tightened from the inside against a washer to prevent it pulling through. This single attachment has been enough to keep it upright through storm and gale for 12+ years and made it easy to take down when I needed to repair it in 2021.

The simple seat is made of four planks of 2×4 treated timber, supported on a simple framework at each end

2021 Renovation

In spring 2021 we renovated the fence that runs behind the arbour, replacing the thirteen year old feather-edge panels with a bespoke, modern-style horizontal t&g boards. This necessitated moving the arbour, at which point it was discovered that rot had set into the base and made its way up the first 6 inches of the frame. My solution was to saw off the bottom eight inches of the arbour and replace it with an apron of rot-proof Accoya (8″x2″). The rot had got in from the base on which the arbour was sat. That old base had been treated 2″x4″ timbers in ground contact. Inevitably, they had rotted and the rot spread into the arbour’s timbers. Before re-erecting the renovated arbour, I cast a concrete base for the new accoya apron to sit on.

The arbour after it was renovated in 2021

Part of the cause of the rot was those exposed structural timbers. While the recessed panelling looks particularly nice it does funnel rain towards the exposed posts. This is more of a problem at the sides than the front, as air circulation is poorer where plants grow up the sides. Also, the slope of the roof (which does not have gutters) directs rain to these sides. Because of this, I decided to add external cladding to the sides so that water no longer collects around the base of the no-longer exposed posts. The front framework is still exposed, but far less water gathers here and it is open to the air so dries much more quickly.

Hopefully that will give the arbour at least another 15 years of serviceable life.