Bases para casetas de jardín
Una base para caseta sin hormigón
Plana, firme y drenante en una tarde. Las rejillas IBRAN proporcionan una base para caseta que mantiene el suelo seco y la estructura a escuadra, sin amasado, sin encofrado y sin esperas de fraguado.
Por qué la base importa más que la propia caseta
Las casetas de jardín casi nunca fallan por la caseta en sí. Fallan por lo que hay debajo.
Coloca una construcción de madera directamente sobre tierra, sobre losas asentadas en arena o sobre unos bloques en las esquinas, y ocurren dos cosas. El terreno se mueve, la estructura se deforma, la puerta deja de cerrar y la cubierta empieza a dejar pasar el agua. Y la humedad se acumula contra los largueros inferiores porque nada drena por debajo, de modo que el suelo se pudre desde abajo mientras las paredes siguen en perfecto estado.
Una solera de hormigón resuelve el movimiento, pero introduce su propio problema: es impermeable, así que el agua que llega a ella tiene que ir a algún sitio, y normalmente acaba formando un charco en el perímetro que mantiene la madera húmeda de todos modos. Además, supone una jornada de trabajo, una hormigonera, un suministro de árido y una base permanente que permanece aunque la caseta desaparezca.
Una base de rejilla resuelve ambos problemas. La grava confinada proporciona una plataforma firme y nivelada que no asienta de forma irregular, y el conjunto permanece totalmente permeable al agua, de modo que la lluvia drena directamente y el aire circula bajo la construcción en lugar de acumularse humedad contra ella.
Aplicaciones habituales
- Casetas de jardín, desde 6x4 en adelante
- Talleres y edificios para aficionados
- Almacenes de bicicletas y cortacéspedes
- Leñeras y zonas para contenedores
- Casetas de plástico y metal
- Gallineros y alojamientos para animales
- Bases para depósitos de gasóleo y equipos
- Sustitución de soleras o bases de pavimento deterioradas
Resumen técnico
| Subbase | 75-100mm de zahorra compactada para una caseta de jardín estándar. Mayor espesor para talleres o contenidos pesados |
| Relleno | Mezcla graduada 6-14mm, angular y limpia, enrasada con la parte superior de las celdas |
| Excavación total | Aproximadamente 110-140mm, según la profundidad de la rejilla y la subbase |
| Tiempo | Una tarde para una base de caseta estándar, una sola persona |
| Herramientas | Pala, rastrillo, sierra de mano y compactador si se alquila uno |
| Drenaje | Totalmente permeable al agua. El agua drena a través en lugar de acumularse alrededor de la construcción |
| Vida de diseño | 25 años, sujeto a instalación documentada |
| Material | Polipropileno 100% reciclado, fabricado en la UE con polímeros reciclados |
Por qué supera a las alternativas
Frente a una solera de hormigón: sin amasado, sin encofrado, sin tiempo de fraguado, sin retirada de escombros y sin estructura permanente que quede si se retira la caseta. También resulta considerablemente más económica para una construcción de jardín estándar si se tiene en cuenta el árido, el cemento y el alquiler de maquinaria.
Frente a losas de pavimento: las losas asentadas en arena asientan de forma individual, y cuando una baja el resto de la construcción la sigue. Una base de rejilla distribuye la carga sobre toda la huella, de modo que la plataforma se mantiene plana como una sola pieza.
Frente a largueros de madera sobre bloques: los bloques se hunden en terreno blando a distintas velocidades, y los huecos entre ellos acumulan hojas y humedad. Una base continua no tiene ese problema.
Frente a no hacer nada: es la solución más habitual y la razón por la que tantos suelos de caseta están blandos en las esquinas.
¿Qué profundidad de rejilla elegir?
La cifra de una rejilla indica la profundidad de la capa de grava confinada. Para construcciones de jardín las cargas son moderadas y se distribuyen a través de los largueros, por lo que la opción más superficial suele ser la correcta.
- IBRAN®-X30 para la mayoría de casetas de jardín. La excavación más superficial, menos grava y menos tierra sobrante que gestionar, algo importante cuando el único acceso al fondo del jardín es por el interior de la vivienda.
- IBRAN®-X40 para talleres más grandes, contenidos pesados o cuando la base también sirve de paso para carretillas o cortacéspedes.
- IBRAN®-X50 cuando un vehículo vaya a acceder a la base, como en edificios tipo garaje o almacenes de tractores cortacéspedes con acceso frecuente.
Especificar más profundidad de la que necesita una caseta es grava que pagas por enterrar y acarrear hasta el fondo del jardín.
Elección de la grava
Utiliza una mezcla graduada 6-14mm, angular y limpia. Una celda más superficial requiere un tamaño máximo de árido más fino para quedar completamente rellena, y una mezcla compacta mejor que un tamaño único porque la gravilla más pequeña rellena los huecos entre los áridos mayores.
Esa densidad es lo que proporciona una plataforma plana y estable. Una celda completamente rellena transmite la carga a través de la grava hacia el terreno subyacente; una celda parcialmente rellena la transmite a través del plástico, y bajo un larguero que soporta una esquina de la construcción eso se traduce en un hundimiento.
Evita la gravilla redondeada tipo guijarro, que rueda en lugar de trabar, y cualquier material con finos o polvo, que sella la superficie e impide el drenaje. La permeabilidad al agua es la mitad de lo que estás comprando.
How it goes in
- Mark out the base. Make it larger than the shed footprint by at least 100mm on every side, so rain running off the roof lands on stone rather than on soil next to the timber.
- Check the ground falls away from the building position rather than towards it, and clear any turf, roots and soft soil down to firm ground.
- Excavate to your total depth: sub-base plus grid depth. For a typical garden shed that is around 110-140mm.
- Lay a woven geotextile across the dig, lapping joins by at least 300mm and taking it up the sides. This stops the sub-base mixing into the soil beneath and keeps the base performing.
- Add the sub-base and compact it. 75-100mm of MOT is ample for a garden shed, compacted in one or two layers rather than tipped and levelled.
- Blind with a thin layer of grit sand and screed it level. Check it with a straight edge and a spirit level in both directions: this is the layer that decides whether your shed door shuts.
- Push-fit the grids together across the base, cutting the perimeter to line with a hand saw.
- Fill the cells with a 6-14mm graded blend, level with the cell tops, and brush it in so no cell is left hollow.
- Set the shed on bearers across the base and check it is square and level before fixing anything together.
Full step-by-step detail is in our installation guides.
Make the base bigger than the shed
This is the single most useful thing to get right, and it costs almost nothing at the time.
A shed roof throws water off its edges. If the base stops at the shed footprint, that water lands on soil, splashes soil back up against the boards, and keeps the bottom of the building permanently damp. Extend the base 100mm or more beyond the shed on every side and the runoff lands on free-draining stone instead, where it disappears.
The margin also gives you somewhere to stand while you build, somewhere for the door to swing over, and a clean strip to walk round the building for maintenance rather than treading a muddy path into the lawn.
If the shed has a door on the long side, take the base out further on that side still. It becomes the threshold you stand on every time you open it.
Keeping the floor dry
Rot in a shed floor almost always starts underneath, and it starts because moisture has nowhere to go.
Set the building on bearers rather than directly on the base, so there is an air gap under the floor. Run the bearers in the direction that lets air pass through, keep vegetation cut back from the sides, and resist the temptation to pile logs, bags or bin bags against the walls, which traps damp exactly where the timber is most vulnerable.
With a permeable base, water that gets under the shed drains away and air moves through. That combination is what keeps a timber floor sound for decades rather than years.
Sloping gardens
Few gardens are flat, and a shed base has to be.
For a gentle slope, dig into the high side rather than building up the low side. Cut-and-fill is fine for the last little bit, but material you have added is always less stable than ground you have not disturbed, so take more off the top than you put on the bottom.
On a steeper slope you will need a retained edge on the high side, and it is worth stepping back and checking whether the shed wants to be somewhere else. A level spot ten feet away is usually cheaper than a retaining structure.
Get it right first time
The one thing worth knowing: level and square, checked twice.
Almost every complaint about a shed comes back to the base not being flat. The door binds, the windows will not shut, the roof panels do not meet, and the building racks slowly out of shape.
Screed the blinding layer properly, check it with a straight edge in both directions and diagonally, and check the diagonals of your marked-out area match before you lay a single grid. Ten minutes with a spirit level and a tape saves a decade of a door that never quite closes, and unlike everything else on this list it cannot be fixed once the shed is up.
Ask our engineer
Questions about depths, base sizing, sloping ground or which system fits your building? Ask below, or get in touch directly.
Common Questions
Is a grid base as good as a concrete shed base?
For a garden building, better in most respects. Confined stone gives a firm level platform that spreads load across the whole footprint, and unlike concrete it stays fully permeable so rain drains through rather than pooling round the building and keeping the timber wet.
There is no mixing, no formwork, no curing time and no permanent structure left behind if the shed goes.
How deep do I need to dig for a shed base?
Around 110mm to 140mm in total for a typical garden shed, made up of 75mm to 100mm of compacted MOT sub-base plus the grid depth. Larger workshops or heavy contents need more sub-base.
It is a shallow dig, which matters when the spoil has to be carried through the house to get out of the garden.
How big should a shed base be?
Larger than the shed footprint by at least 100mm on every side. A shed roof throws water off its edges, and if the base stops at the footprint that water lands on soil and splashes back against the boards. Extending the base means runoff lands on free-draining stone instead.
Take it out further still on the door side, since that becomes the threshold you stand on.
What size gravel should I use for a shed base?
A 6mm to 14mm graded blend, angular and clean. A blend packs tighter than a single size because the smaller stone fills the gaps between the larger, and that density is what gives a flat stable platform.
Avoid rounded pea shingle, which rolls rather than interlocking, and anything carrying fines, which binds the surface and stops it draining.
Which grid depth do I need for a shed?
The 30mm grid suits most garden sheds: the shallowest dig, the least stone and the least spoil. Use 40mm for larger workshops, heavy contents, or where a wheelbarrow or mower route runs up to the base.
Use 50mm only where a vehicle will drive onto it, such as a garage-style building.
Do I still need bearers under the shed?
Yes. Set the building on bearers rather than directly on the base so there is an air gap under the floor. Rot in a shed floor almost always starts underneath, and it starts because moisture has nowhere to go.
A permeable base drains water away and bearers let air move through, which is the combination that keeps a timber floor sound.
Can I build a shed base on a slope?
Yes. For a gentle slope, dig into the high side rather than building up the low side, since material you have added is always less stable than ground you have not disturbed.
On a steeper slope you will need a retained edge on the high side, and it is worth checking whether a level spot a few feet away would be cheaper than a retaining structure.
How long does a shed base take to lay?
An afternoon for a typical garden shed, working alone. The grids push together by hand with no tools or fixings, and the base is usable immediately: there is no curing time, so the shed can go up the same day.
Most of the work is the digging.
Do I need planning permission for a shed base?
Garden buildings are usually permitted development subject to size, height and position limits, and a permeable base does not add to surface water run-off in the way an impermeable slab does.
Rules differ across the UK and are tighter for listed properties and conservation areas, so check with your local planning authority if you are unsure.
Can I put a grid base over an existing slab or paving?
Yes, provided the existing surface is sound and water has somewhere to go. Fill any holes, check your finished levels, and use the shallowest grid to keep the build-up down.
If the slab is badly broken or holds water, it is usually better to lift it, since a base that cannot drain gives up the main advantage of the system.
Ask our engineer
Questions about depths, sub-base, edging or which system fits your project? Ask below.
