Log Stores: Size, Siting and the 20% Moisture Rule

A log store has one job: to take wood that is wet or half dry and hand it back, months later, at a moisture content low enough to burn cleanly. Most of the log stores sold in the UK look the part and do that job badly, because they are built like small sheds when what firewood needs is a roof and a lot of moving air. This covers what separates a good outdoor log store from a pretty box, how big yours needs to be, where to put it in the garden, how to stack it, and when a log store needs planning permission.

Why a log store matters: the 20% line

Dry firewood is defined by a number. Defra’s practical guide to open fires and wood-burning stoves says dry wood should have a moisture content of 20% or less, and it suggests freshly chopped wood is left to dry for up to two years before burning. Wet wood burns cooler, makes more smoke and particulates, and coats the stove glass and the flue with tar.

The rules on buying wood follow the same line. Since May 2021, wood sold in England in volumes of up to two cubic metres has to be certified Ready to Burn under the Woodsure scheme, meaning a moisture content of 20% or less. Larger loads can still be sold wet, but they must come with advice on drying them. So if you buy in bulk to save money, or you cut your own, the log store is what gets the wood from wet to legal-to-sell dry. Even kiln-dried logs need a dry store, or they will take moisture back from the air and rain over the winter.

What makes a good log store

Four features do almost all of the work, and you can check any log store for sale against them in a minute.

Empty timber log store on a lawn with slatted sides, a slatted roof and a floor raised off the ground — An empty timber log store showing the features that matter: gapped side slats, a roof that overhangs, and a floor lifted clear of the ground. | Large Log Store by best4garden- wood products (CC BY-SA 2.0), via Flickr, https://www.flickr.com/photos/84250859@N08/9015535185

A roof that overhangs. Rain is the main enemy, and it rarely falls straight down. A roof that stops flush with the front lets driven rain run onto the top of the stack. Look for an overhang at the front of at least 20cm, and a fall to the back so water sheds away from the logs.
Open or slatted sides. Wood dries by losing moisture to moving air. Solid-sided stores with doors trap damp air around the stack, which is how you get mould and logs that never drop below the mid twenties. Slats with gaps, or fully open sides, let the wind through.
A raised, slatted floor. Logs sitting on soil or paving wick up ground moisture and rot from the bottom row. A floor lifted clear of the ground, with gaps between the boards, keeps the base dry and lets air rise through the stack.
An open or part-open front. Doors look tidy but slow drying. If you want a front, a slatted one or a hinged panel you leave open through spring and summer is the compromise.

After that, it is about build quality. Pressure-treated softwood is the usual material and is fine; check the frame is thick enough not to rack under a full load, as a cubic metre of seasoned hardwood logs weighs several hundred kilograms. Metal stores work well if they keep the open sides and raised floor. Avoid anything that is essentially a plastic storage box: it will keep the rain off and keep the moisture in.

Log store sizes: how big should yours be?

Size a log store by volume, and be careful which volume you mean. Firewood is sold loose, tipped into a bag or a trailer, but it is stored stacked. Stacked logs sit much tighter than loose ones: the firewood trade’s usual conversion is that one cubic metre of stacked logs equals about 1.67 cubic metres loose. Turned the other way, a one cubic metre bulk bag of loose logs stacks down to roughly 0.6 of a cubic metre.

To work out what a store holds, multiply its internal width, depth and stacking height. A store 1.2m wide, 0.6m deep with 1.5m of stacking height holds about 1.08 cubic metres of stacked logs, or a little under two bulk bags of loose logs delivered. Depth matters more than it looks: a single row of logs around 25cm long dries faster than a stack three logs deep, so a long, shallow store beats a deep cube for the same volume.

If you are drying your own wood over two summers, the easiest system is two stores, or one store split into two bays: this year’s wood seasoning in one, last year’s dry wood being burned from the other. For small gardens, a slim store under 40cm deep along a fence holds a surprising amount without dominating the space.

Where to put a log store in the garden

Put it where the weather will help rather than hinder. That usually means:

Sun and wind. An open, sunny spot with a breeze dries logs far faster than a damp shaded corner behind a shed. In most UK gardens a south or west facing position gets both.
Front facing away from the prevailing weather. Much of the UK gets its rain on westerly and south westerly winds, so if the store is exposed, turn the open front away from them or give it more roof overhang.
A small gap from the house wall. A store tight against a wall cuts off airflow at the back and can hold damp against the brickwork. Leave a gap, and never let a log stack bridge a damp proof course or cover an air brick.
Close enough to fetch from in the dark. Keep a small indoor basket or a second small store by the back door stocked from the main store, so the main one can sit where it dries best.

A log store can also go inside a larger outbuilding, a lean-to on the side of a garden room or a bay of a combined shed and log store. That works as long as the log bay itself keeps its open front and slatted sides.

How to stack logs so they dry

A few habits make a real difference to how fast a stack dries:

Split logs before stacking. Wood dries mainly through the cut ends and split faces; bark slows it down. Rounds over about 10cm across dry far quicker once split.
Stack in single rows with the cut ends facing the open front, leaving small gaps rather than packing tight.
Put the newest, wettest wood at the back or in the seasoning bay, and burn from the driest.
Keep the top of the stack a few centimetres below the roof so air can move across it.
Check before you burn. A moisture meter is cheap. Split a log and test the fresh inside face, not the outside, and burn it only once it reads 20% or less.

Softwoods such as pine and spruce usually season faster than dense hardwoods like oak, which can need the full two years. A store with good airflow shortens that; a closed box lengthens it.

Do you need planning permission for a log store?

Most garden log stores do not need planning permission. A freestanding log store counts as an outbuilding, and in most houses outbuildings are allowed under permitted development within limits on height and position. The two that catch people out are height near a boundary (within two metres of a boundary the whole structure must be no taller than 2.5 metres) and position, since an outbuilding cannot sit forward of the principal elevation of the house without permission. Stores in the front garden, at listed buildings or in conservation areas and other designated land deserve a check first. The Planning Portal’s outbuildings guidance sets out the full rules, and we cover the same limits in more detail in planning permission for a garden shed, which apply in the same way.

Leases and new-build estate covenants are a separate question. A covenant can restrict structures in front gardens regardless of planning law, so read your deeds if you are on a newer estate.

For more on sheds, garden rooms and other outbuildings, see the rest of Best Garden Room.

Frequently asked questions

Should a log store have sides?

It should have sides that let air through. Slatted or gapped sides keep most rain off while the wind dries the logs. Solid sides and closed doors trap damp air around the stack and slow drying.

Should a log store face north or south?

Where you have the choice, put it in a sunny, breezy spot, which in most UK gardens means south or west facing. If that exposes the open front to driving rain, angle it away from the prevailing wind or choose a deeper roof overhang.

How long do logs take to dry in a log store?

Defra’s guidance is that freshly cut wood may need up to two years to dry. Split softwood in a well ventilated store can be ready sooner; dense hardwood such as oak often needs the full time. Test with a moisture meter and burn at 20% or less.

Can you store logs against a house wall?

You can, but leave a gap behind the store for airflow, keep it clear of air bricks, and never let the stack sit above the damp proof course against the wall. A store standing slightly off the wall dries logs better and keeps the brickwork drier.

Should you cover logs with a tarpaulin instead of a log store?

A tarp over the top only, with the sides left open, is a reasonable stopgap. Wrapping a stack fully in plastic traps moisture and causes mould, so it does more harm than good.

What size log store do I need for a cubic metre of logs?

A delivered cubic metre of loose logs stacks down to around 0.6 of a cubic metre, so a store with about 0.6 to 0.7 cubic metres of stacking space will take it. For example, 1.2m wide by 0.4m deep by 1.3m high gives about 0.62 cubic metres.