Axter Hydropack and Sedum Mat Installation and Maintenance Guide 1

AXTER HYDROPACK AND SEDUM MAT

INSTALLATION AND MAINTENANCE

GUIDE

June 2009

HYDROPACK

HYDROPACK trays are designed to be placed next to each other directly onto the waterproofing

membrane.

HYDROPACK trays are linked together using the attachment system between modules on the “male”

sides of each tray.

It is important to position the ‘V’ shaped attachment profiles

carefully so that the trays are correctly attached with no space

between them and so that water can pass easily from one tray

to another. (The fixing system is designed to allow circulation

of water from tray to tray). If there is a space between two trays it is because a ‘V’ shaped

hook is not in the correct position. In this case lift the tray and

re-position it so it slots into the neighbouring tray.

DIRECTION IN WHICH TRAYS SHOULD BE LAID: Installation should take place from left to

right by positioning the first tray with “male” hooks pointing to the edge of the roof (towards the verge).

Install subsequent trays in a row before coming back to install the adjacent row, and so on.

“male” side of

the tray

Axter Hydropack and Sedum Mat Installation and Maintenance Guide 2

Slide each tray carefully into position next to the neighbouring tray without allowing too much of an angle

during the installation procedure; this reduces the risk of catching the filter layer of the adjacent tray on

the fixing lip situated at the base of the attachment channels.

INSTALLATION PATTERN

It is not necessary to install the HYDROPACK trays in a staggered formation. This would make the

installation procedure more complex and would necessitate detailed and lengthy cutting along upstands.

We recommend a traditional pattern of installation (corner to corner, side by side).

NOTE: the trays are designed to allow them to be joined in a perpendicular fashion short side with long

side) to allow a simple installation pattern.

NO! OK!

Axter Hydropack and Sedum Mat Installation and Maintenance Guide 3

SLOPING ROOFS

When laying Hydropack on slopes > 10° provision must be made to restrict slippage. This is normally in

the form a perforated metal angle bonded to the deck at a height just below that of the HYDROPACK

tray.

STERILE AREAS

Codes of practice governing green roof areas require that an area of a minimum 40cm square with no

sedum be left around rainwater outlets.

A min 40cm wide strip must also be left round upstands and at edges to facilitate water run-off, reduce

fire risk and to allow access to waterproofing details.

When the slope of the roof is greater than 3%, special measures should be taken in accordance with the current standards.

Green zone

Sterile zone

Separation screen

Vent pipe

Rain water outlet

Movement joint

Axter Hydropack and Sedum Mat Installation and Maintenance Guide 4

These sterile areas should then be filled with min 20 / 40 washed rounded gravel.

Where the edge of the roof is not protected by a parapet or other upstand then a perforated metal or

aluminium angle must be bonded to the waterproofing.

WATERING AFTER INSTALLATION

HYDROPACK trays are delivered with varying levels of substrate saturation and water levels in the water

reservoir (depending on the amount of rainfall prior to despatch from the nursery). Transportation of the

trays also leads to a certain amount of “stress” of the plants.

Watering should take place once the trays have been installed. This will fill the water reservoir in the trays.

A site visit should take place approximately one month after installation to check that the vegetation is in

good condition.

See Maintenance Programme on page 6.

Axter Hydropack and Sedum Mat Installation and Maintenance Guide 5

SEDUM MAT

1 Unroll the pre-cultivated mats on the substrate ensuring that:

• the rolls are unrolled in a staggered formation, as shown below.

Roll size: 2m x 1.2m approximately.

mat

• that the sections of mat are positioned as closely as possible to each other, bearing in mind

that there will be a slight shrinkage of the mat in dry periods.

• the substrate on which the mat is installed is not deformed in any way (to avoid air pockets

appearing under the sedum mat). To achieve this, walk along the side of the rolls already

installed and press down with a rake before unrolling more mat.

It is imperative that the mat is unrolled within 24 hours of arrival on site at the latest. If for some reason

installation will not be finished within this time, do not leave the mat rolled up. The vegetation will

wither through lack of air.

2 Cut the mat where necessary with a sharp cutter or knife, taking care not to damage the

waterproofing membrane during the process.

A site visit should take place approximately one month after installation to check that the vegetation is in

good condition.

The recommended number of inspections is two per year.

See Maintenance Programme on page 6.

Cut sections

Axter Hydropack and Sedum Mat Installation and Maintenance Guide 6

MAINTENANCE PROGRAMME

Two visits should be made after installation of the vegetation:

• the first a month later to ensure that the vegetation is in a good condition and to observe any anomalies.

• the second 3 to 6 months later to verify the root growth and to effect any reinstatement that may be necessary.

After the initial maintenance described above, during the first year it is recommended that at least two

maintenance visits are made to the roof each year. The first should be at the beginning of spring and the

second in the autumn, after leaf fall.

The table below gives an indicative work plan for each visit.

During installation

Standard maintenance

Remove all vegetation, debris etc from rainwater outlets and on the

sterile areas. � �

Manually remove any herbaceous material that may be detrimental to

the waterproofing (woody shrubs…). � �

Remove any leaves (leaves may stifle the vegetation and block rain

water outlets). � �

Manually remove any aesthetically unpleasing vegetation which may

affect the waterproofing membranes (e.g. grass..).

Optional

Dead head the sedum. Optional Optional

Use of Fertiliser: It is recommended that a slow release fertiliser is

applied to the Hydropack at the start of spring and to the sedum mat

twice a year (25gm/m2), preferably in March and September.

A product such as Osmocote Exact (produced by Scotts) with a

formula NPK 15-9-9 should be applied by a hand spreader to ensure

even coverage.

�

Water after installation of the packs/mats: especially during

prolonged dry periods or periods of high temperatures. Take care

not to over water.

�

Water during summer periods or prolonged dry periods. As required

Re-plant any missing sedum fragments . As required As required

Minimum number of maintenance visits per year. 2

Axter Hydropack and Sedum Mat Installation and Maintenance Guide 7

Important reminders:

The principal conditions that restrict growth of sedum:

- An excess of shade

- Excess of water or prolonged dry periods

- The proximity of glazed bays

Access to water is required for each roof. This will enable watering to take place when required (notably during times of prolonged dry weather).

For further information or assistance please do not hesitate to contact Axter Ltd.

Axter Ltd, West Road, Ransomes Europark, Ipswich Suffolk IP3 9SX Tel: 01473 724056 Fax: 01473 723263; email: sales@axterltd.co.uk

www.axter.co.uk