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Block Deck

Block Deck Garden Room Base

Block Deck

One of the most important factors in designing a Garden Room, whuch is often overlooked, is how your building is going to sit on the ground without it being effected by damp and condensation as well as being able to withstand the potential uplift from storm force winds. Many garden room buildings have a simple timber frame base placed on patio slabs, which is prone to decay.

The Block Deck base designed by Foundation Buildings is part of your buildings’ structure. It is a galvanised steel structure which is simply assembled which is positioned inside the damp proof membrane and surrounded by insulation, to prevent corrosion caused by condensation.

It is important that your garden building can withstand the uplift forces from gale force winds and also solves the issue of timber floor joists being exposed to rainwater and damp. The majority of garden room buildings are constructed from timber and the timber joists which make up the floor deck, are often sat on a concrete slab or patio slabs, where rain water finds its way underneath the building and water can penetrates the floor timber structure, causing mould, mildew and decay.

Block Deck is especially suitable for flat sites where access is difficult. Ideal for the “man cave”, home office, outdoor gym, play room, home bar or just for additional storage space in your garden. All components to assemble the Block Deck framework are supplied. All steelwork is manufactured the correct lengths to suit your garden building with a full package of fixings and assemble instruction to make assembly of the framework less of a daunting task.

As many garden room buildings are constructed within the planning permission permitted development rights, the height of your building structure is critical. The Block Deck framework is ground bearing, therefore the height of your floor can be whatever you want it to be, dependent on your depth of excavation and thickness of insulation, but generally, 150mm above the surrounding ground level is recommended to prevent splash back from rainwater effecting the bottom of the wall cladding and glazed doors.

Rainwater splash back can be reduced by having a 150mm wide gravel margin placed around the building, rather than having decking or garden slabs set right up to the building.

One of the key factors in designing the Block Deck frame was its ability to provide an in-built Dead Weight to the structure to ensure these lightweight garden room structures withstand the wind loadings and uplift forces which will be imposed on it. The Block Deck base has a steel platform around the perimeter, which allows the building framework to be securely fixed to the Block Deck steelwork. The timbers are simply clamped into position and holes drilled through both the timbers and the steelwork and coach bolts are fitted to bolt the timbers into position.

The Block Deck foundation base is fully surrounded by insulation. It sits on a base of insulation and the perimeter of the framework is designed to accept 50mm thickness of side insulation, which butts up to the base insulation below. This helps prevent issues with condensation caused by temperature differences. In addition, it is much easier than cutting insulation between joists.

This image shows the typical Block Deck installation. This assumes the ground is well compacted virgin soil on a flat, level site. The depth of excavation is dependent on the ground conditions of the site and the thickness of the insulation required. Generally this is around 250mm deep. If you have any queries regarding types of insulation, material choices or your existing ground conditions, please drop us a line.

Comparing Block Deck to other bases

Concrete slab

  • No requirement for ready mix concrete or pumping.
  • Concrete bases can be out of square and not level, causing issues with building alignment.
  • Concrete can cause issues if poured in cold, hot, windy or wet weather.
  • Curing problems can occur such delamination, shrinkage cracks or next doors cat!
  • To install perimeter insulation to a concrete slab, it is normal practice to construct a brick dwarf wall up to floor level.
  • Fixing the building structure to the slab at the perimeter can cause issues with fixings close to the edge of the concrete.
  • Concrete needs to cure before fixings can be drilled into it.

Screw piles

  • Screw piles are only suitable for certain ground conditions or strata.
  • Airflow is required below timber joist floor which impacts on overall build height.
  • Requires accurate setting out to ensure screw piles are positioned correctly.
  • Piles generally 750mm long and require specialist tools to install.
  • Obstacles below the surface are discovered blind and will need to be dug out and removed.
  • Quantity of floor joists and timber section sizes increased to enable spanning of screw pile locations, at 1-1.2m intervals.
  • Vermin can live in void beneath structure, which is required for airflow.
  • Underside of timber is exposed.

Timber joist deck

  • Insulation panels need to be cut and fitted between joists.
  • Timber sizes varying between suppliers.
  • Waste caused by knots, cracks, warping or natural timber defects.
  • Decay caused by timber exposed to elements and placed on wet flag stones or concrete slab.
  • Waste material caused from supply of standard lengths, rather than required lengths.
  • Warping and distortion of timber due to differences in humidity, temperature and the seasons.
  • Undersize or insufficient timber joists can lead to springy floors.
  • Perimeter floor timbers need to be thick enough to support wall timbers (usually 100mm thick).

Block Deck advantages

  • Designed to be assembled by a competent trades person or self builder following the assembly and construction instructions provided.
  • Ideal for gardens which are level or have poor access.
  • Lightweight – a 6m length of Block Deck steel is only 23kg.
  • All steelwork to the Block Deck base is supplied at the correct length with pre-drilled holes provided for ease of assembly.
  • All fixings to assemble Block Deck foundation framework is supplied.
  • No timber floor joists – building structure is fastened directly to Block Deck frame.
  • Chipboard flooring is screwed directly onto Block Deck steel.
  • Finished floor level can be varied to suit insulation thickness and garden room build heights.
  • All steelwork is fully galvanised and is enveloped within DPM and insulation.
  • Floor deck is ground bearing, no springy floors due to unsupported timber joists, ideal for home gyms or where heavy equipment is used, i.e. pool tables.

Block Deck & SIP buildings

The Block Deck foundation base can be supplied separately, for you to construct your own building framework to, or complete with a SIP (Structural insulated panel) building.

Each Block Deck base is bespoke and is designed to suit the footprint of your building. All sections are made to measure and all holes are pre-punched to aid assembly. The only holes that are not pre-punched are the holes for fixing your timber sole plate to the Block Deck framework. This is easily done by clamping the timbers in place, drilling through the timber and steelwork and bolting the sole plate timbers into place using coach bolts.

Please provide details of your proposed construction method and sizes so that we can provide you with an accurate quotation.

Insulated block deck foundation base for garden room buildings

Foundation building have designed a fully insulated floor and foundation system, called “Block Deck”. This is ideally suited to Garden Room buildings and provides a fully insulated envelope, below and above. Block Deck is a very practical solution and is quick and easy to install.

The Block Deck base is manufactured specifically to suit the size of your building and your building is simply bolted onto the block deck framework without any requirement for additional foundations.

Installation of block deck foundation base

Block Deck installation

Simply strip off your top soil. Lay a hardcore base. Blind with sand. Cover with DPM. Lay insulation sheets. Cover with protective OSB3 sheeting. Assemble the Block Deck base. Infill Block Deck grid with concrete blocks. Bed in blocks with pea gravel.

The Block Deck base provides the following advantages:

  • Fully insulated beneath the Block Deck base and to the sides
  • Designed specifically to suit the size of your building
  • No floor bounce from suspended timber joists
  • No foundations or ready mix concrete
  • No waiting for concrete cure times
  • No requirement for separate timber floor deck
  • Does not require airflow beneath the floor deck
  • No concrete floor slab or screw pile installation
  • Quick and easy to assemble with no waste

Fully insulated garden room floor

The Block Deck base can be used for timber frame, SIP panel or lightweight steel frame buildings. The building is simply fixed directly to the steel framework. There is no need for a separate timber floor deck, the chipboard flooring is simply fixed to the Block Deck framework using special drill point screws called Tek screws.

The Block Deck base framework is infilled with 100mm standard high density concrete blocks. This provides a downward force to the structure, which counters the wind uplift of the garden room structure to ensure your garden room building stays where it should be, whatever nature throws at it.

Foundation Buildings can deliver Block Deck bases throughout the UK.

We will create the Garden Room building that you deserve!

Please contact us:

Phone 07538 775060

We look forward to hearing from you!

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