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Basic requirements for permanently sealed building entries

Illustration of a building wall with service lines

Fig. 1: Illustration of a building wall with service lines

1. Introduction

Basic information on building waterproofing

In general, supply to and disposal from a building is implemented using service lines laid underground. The building shell needs to be penetrated in order to introduce these lines into the building.

In turn, the building shell is provided with waterproofing to protect the people, objects and of course the building itself against external influences, and especially penetrating water. This means that the building entry also penetrates the waterproofing.

It is possible to provide a gastight and watertight transition between the building waterproofing and the service line using an appropriate sealing system, also known as a entry system. This reinstates the building waterproofing. The building waterproofing, and therefore also the entry system, is logically located on the outside of the building, which means that access to the entry system is often extremely restricted or even no longer possible. This means that a large proportion of all entry systems have to function without maintenance. Depending on the building usage the lifespan of the building, and therefore also of the entry system, can be up to 50 years. This makes the high quality requirements on entries systems obvious.


Fig. 2: Soil moistureFig. 2: Soil moisture

Fig. 3: Non-standing seepage water

Fig. 3: Non-standing seepage water

Fig. 4: Temporary standing seepage water

Fig. 4: Temporary standing seepage water

Fig. 5: Pressing water

Fig. 5: Pressing water

2. Load cases in structures contacting the ground

Definition, determination, influencing factors

The type and method of building waterproofing is dependent on the load case acting on the building.

The designer decides which load case is acting by calculating the design water levels (highest groundwater level to be expected +30 cm safety factor). Normally, a minimum period of between 20 and 30 years is assumed in this case. On top of this, the water management influencing factors should also be taken into account. Irrespective of these, changes (height increases) to the moisture load can still occur, for example caused by:

  • extreme weather conditions with high precipitation levels,
  • increase in groundwater levels through reconditioning work to sewage lines,
  • surface sealing,
  • soil substance (e.g. mining areas) or
  • water management influencing factors (e.g. shutting down of pumps).

DIN 18195 describes the following load cases which are described below in more detail:

2.1 Soil moisture and non-standing seepage water

Soil moisture is understood to be capillary-bound water which is also capable of moving against the forces of gravity due to capillary forces present in the soil (suction water, retained water, capillary water). However, non-standing seepage water from rainfall is also included in the case of vertical wall elements. A requirement for the above is a strongly permeable soil (sand, gravel, with a water permeability coefficient of k > 10-4 m/s or a permanently-functioning drainage system in acc. w. DIN 4095.

2.2 Non-pressing water

Non-pressing water is understood to be water in drop and liquid form which does not exert, or exerts very little, hydrostatic pressure onto the waterproofing (precipitation, seepage or process water). This applies to the waterproofing of horizontal and inclined surfaces in addition to wet areas (e.g. baths with floor drainage) with irrigation heads of up to 100 mm (under greened roofs). This means that it is not used for external walls in contact with soil.

2.3 Temporarily standing seepage water

Standing seepage water is understood to be water which exerts a temporary hydrostatic pressure.

2.4 Pressing water

Pressing water is understood to be water which exerts a permanent hydrostatic pressure.


 

Table: Recommended minimum structural component thicknesses (information in mm) [7]

No. Structural element Load Class 1 2 3
Implementation type
In-situ concrete Element walls Precast elements
1 walls 11 240 240 200
2 22 200 2403 100
3 base plate 11 250 200
4 22 150 100
1 Loading Class 1: Pressing and non-pressing water in addition to temporary standing seepage water.
2 Loading Class 2: soil moisture and non-standing seepage water.
3 Reduction down to 200 mm is possible under the implementation of special concrete and implementation measures.

Fig 6

Fig. 6: Working model for moisture conditions in a concrete componentcross-section with one-sided application of pressing water(concrete C30/37 (B35 water-impermeable) w/c ≤ 0.55) basedon Beddoe / Springenschmid

3. Types of structural waterproofing

3.1 White tank. Water-impermeable structures in concrete (water-impermeable concrete)

The construction of entries in water-impermeable structures made of concrete is regulated by the DAfStb Guideline – Water- impermeable Structures in Concrete issued by the German Committee for Reinforced Concrete. In general linguistic use these building waterproofing systems are known as a “white tank”. The guideline specifies the following with regard to entries:

“All structural joints and entries must basically be designed and implemented as waterproof with suitably adapted systems depending on the loading class.”

The WI Guideline differentiates between two loading classes:
Class 1: pressing and non-pressing water in addition to temporarily standing seepage water
Class 2: soil moisture and non-standing seepage water

There is little information about the implementation of entries, and also few definitions of requirements.

The wall thicknesses are specified depending on the expected water loading (immersion depth) and from the concrete quality (crack sizes and crack frequency).

In this type of building waterproofing it should be noted that this type of building consists of not a waterproof but rather a waterimpermeable wall structure. Water in the form of pressing water can penetrate up to 25 mm into the concrete over its full area.

On top of this, the water can penetrate maximum 70 mm intothe existing capillaries. Water can defuse up to 80 mm into orout of the wall on the wall weather side depending on the moistureconditions.

A core area which prevents water transport from the water sideto the air side (water impermeability) can only be formed if awall thickness of ≥ 200 mm (depending on concrete quality,grain size, reinforcement cover etc.) is chosen. For this reason,the entry system must be provided with a sealing area width appropriateto the load case.

Furthermore, it should be installed on the side of the wall facingthe water so that the water cannot penetrate the wall deeperand therefore so that the core area is lost.

When constructing the apertures for entries using core drillings,the reinforcement is cut. This can result in cracks. These crackshave to be repaired before installing the entry systems, and anyreinforcing steel uncovered in this manner must be protectedagainst corrosion. This means that the use of pipe sleeves isexplicitly recommended. Normally, pipe sleeves are concreted inwhen constructing the structural element.

Entries, and especially the apertures for their use, may never belocated on construction joints. A distance of ≥ 300 mm isrecommended.

Fig. 7a: Sealing layer precast element

Fig. 7a: Sealing layer precast element

Fig. 7b: Sealing layer in-situ concrete

Fig. 7b: Sealing layer in-situ concrete

Fig. 7c: Covering sealing system

Fig. 7c: Covering sealing system

3.1.1 Element walls
Combination walls

Element walls represent a combination of precast concreteelements and in-situ concrete. In this case, two precast segmentsare separated by lattice beams, and the void betweenthem is concreted in with in-situ concrete. The requirements andthe measures to be taken are regulated in the WI Guideline.Such entry systems should be positioned in the sealing layer.

This is generally the in-situ concrete. If surface sealing systemsor special versions of precast concrete segments are used, thesystems can also be located in the outer surface. In this case,clarification with the planner or constructor of the wall is necessaryin advance. In cases of doubt, special entry systems whichcover all the sealing layers can be used.

3.2 Black tank
Waterproofing of non-waterproof structures

Penetration of the waterproofing in structural segments in contactwith soil for cable and pipe entries is mostly regulated byDIN 18195. DIN 18195’s scope is related to the waterproofingof non-waterproof structures or structural segments. The arrangementand implementation of entries is especially regulatedby DIN 18195-9. Building waterproofing of this type is generallyknown as a “black tank”.

Entries must be planned and implemented so that they cannotbe run round or under, if necessary with the help of installationcomponents. The constructive and waterproofing measures necessaryfor this purpose must be adapted to the expected waterloading [3].

The entry must be located so that the structural waterproofingcan be professionally closed off. Components requiring maintenancemust be located and further layers must be designed sothat simple accessibility is guaranteed [6]. The edges of the entrysystem must be free of burrs.

External edges of the connecting elements of glued and weldedflanges in addition to collar constructions should normally be atleast 150 mm from structural element edges and structural elementfillets, and at least 300 mm from structural joints. In casesof loose and fixed flange structures, the distance should be atleast 300 mm from structural element edges and structural elementfillets, and at least 500 mm from structural joints. If thesedistances cannot be adhered to, special structures must beplanned.

Entries may not lose their function if the structural component oradjacent soil layers carry out expected movements, if necessaryspecial measures must be taken in such cases (proper compaction,footings made of lean concrete etc.).

Fig. 8: Tanking membrane with packing (Curaflex C/2/SD/5)

Fig. 8: Tanking membrane with packing (Curaflex® C/2/SD/5)

Fig. 9: Example of fixed/loose flange structure

Fig. 9: Example of fixed/loose flange structure

3.2.2 Entry implementation

The following entry systems are to be used depending on the load case:

3.2.2.1 With the use of tanking membranes

a) Soil moisture and non-standing seepage water

With this load case, the waterproofing is to be connected to theentry with the aid of a bonding flange, a welding flange or acollar with a clamp. The flange width for bonding and weldingflange structures must be between 80 mm and 120 mm dependingon the waterproofing material.

b) Non-pressing water

With this load case, the waterproofing is to be connected to theentry with the aid of a bonding flange, a welding flange, a collarwith a clamp or a loose and fixed flange structure.The loose and fixed flange structure must be made of steel andhave the following dimensions:

  • loose flange width min. 60 mm
  • fixed flange width min. 70 mm
  • material thickness min. 6 mm
  • tensioning bolt or tensioning screws min. M12 with a spacing of between 75 and 150 mm.

The torques with which the construction is to be tightened arespecified in DIN 18195 Part 9 depending on the type of tankingmembranes used. In cases of doubt these must be requestedfrom the manufacturer of the tanking membranes.

When bitumen tanking membranes is used, a steel ring for preventionof bitumen outflow is to be provided. In the area aroundflanges, the tanking membranes may not have any faults, kinksor other uneven features. DIN 18195 also requires packingsconstructed of the same material or material-compatible elastomerson both sides in the case of single-layer, loosely-laid waterproofing.

Practice has shown that thin and/or hard tanking membranescannot be sealed off properly without packings.

c) Temporarily standing seepage water and pressing water

The waterproofing is to be connected to the entry with the aid ofa loose and fixed flange structure for this load case.The loose and fixed flange structure must be made of steel andhave the following dimensions:

  • loose flange width min. 150 mm
  • fixed flange width min. 160 mm
  • material thickness min. 10 mm
  • tightening bolts or screws min. M20 with a spacing of between 75 and 150 mm

The requirements or specifications with regard to torques, limitationsagainst outflow of bitumen, condition of tanking membranesin the area around the flange and packings applyanalog in this case.

Fig. 11: Pipe sleeve system with bonding flange (Curaflex 3001)
Fig. 11: Pipe sleeve system with bonding flange (Curaflex 3001)

Fig. 11: Pipe sleeve system with bonding flange (Curaflex® 3001)

3.2.2.2 With the use of plastic-modified bituminous thick-coating

If waterproofing in the form of trowelable plastic-modified bitumenwaterproof coatings has been applied, the entry can be implementedas follows depending on the load case:

a) Soil moisture and non-standing seepage water

For this load case, the plastic-modified bituminous thick-coating(PMB) can be trowelled on to the entry in the form of a fillet.This implementation variation is only permissible if the serviceline or pipe sleeve is not expected to be subjected to any axialor radial movements over the entire service life. It may be necessaryto roughen the surface in order to achieve sufficientbonding to the service line. This must be agreed in advance withthe service line operator or constructor. Since this option canseldom be guaranteed in practice, implementation using abonding flange is recommended.

Fig. 10: Towelling of fillet type [11]

Fig. 10: Towelling of fillet type [11]

b) Non-pressing water

In this load case, the plastic-modified bituminous thick-coating(PMB) must be applied to a bonding flange using reinforcing inserts,or connected to a loose and fixed flange structure.

Fig. 13: DOYMA Curaflex® 1776
Fig. 13: DOYMA Curaflex® 1776

c) Temporary standing seepage water

A prefabricated installation component made of a bitumencompatibleplastic tanking membranes must be clamped in aloose and fixed flange structure for this load case.In the connection area around the plastic-modified bituminousthick-coating (PMB) this waterproofing sheet must be providedwith a fleece or fabric backing in which the plastic-modified bituminousthick-coating (PMB) can be bedded.

Fig. 12: Connection of PMB to loose and fixed flange structure [11]

Fig. 12: Connection of PMB to loose and fixed flange structure [11]

Such installation components made of tanking membranes are difficult to obtain in normal trade. Other solutions, such as the DOYMA Curaflex® 1776, have proven themselves in this situation.

d) Pressing water

According to DIN 18195, this load case is not permitted forplastic-modified bituminous thick-coating (PMB). However, thisprocedure is recommended by the manufacturers of plasticmodifiedbituminous thick-coating (PMB) and the “Verband derDeutschen Bauchemie”, and should be carried out using a looseand fixed flange structure.


Fig. 14 a: Support with suspension mechanics and sliding element

Fig. 14 a: Support with suspension mechanics and sliding element

Fig. 14 b: Support with suspension mechanics

Fig. 14 b: Support with suspension mechanics

Fig. 14 c: Support with side mechanics

Fig. 14 c: Support with side mechanics

4. Support and service line movements

4.1 Support
Basic fixing methods

Annular gap seals in the form of compression seals can not absorbradial movements in normal cases. In this case, they maynot be used as bearings.

The service lines must be appropriately supported. A range offitting systems are used to absorb such support forces.

These fitting systems can be fixed directly in front of and behindthe wall entry. If fitting to the wall is not possible for static or waterproofingreasons, a support made of lean concrete can beconstructed in front of the wall, for example.

If axial movements are expected in the service lines, special fittingsystems with appropriate slide elements and guide supportscan be used.

Fig. 15 a: Axial displacement

Fig. 15 a: Axial displacement

Fig. 15 b: Angling

Fig. 15 b: Angling

Fig. 15 c: Lateral movement

Fig. 15 c: Lateral movement

Fig. 15 d: Settlement

Fig. 15 d: Settlement

4.2 Service line movements
Possible service line movements in sealing insert

Axial displacement

Movement in the direction of the service line axis/longitudinal axis.
Gasket inserts can sometimes absorb these movements.

Angular deflection

Inclination of pipe axis: The pivot point must be in the centre ofthe sealing insert. Gasket inserts can sometimes absorb thesemovements. It is imperative that clarification is carried out withprofessional experts for each individual case.

Lateral movement

Sideways displacement of service line (radial movement) Thesealing insert is not capable of absorbing sideways displacement.For this reason this type of movement must be ruled out.

Settlement

Building settlement can lead to the displacement or twisting ofpipes. Displacement or twisting cannot be absorbed by the sealinginsert. For this reason, displacement must be ruled out structurally.


References

  1. Normenausschuss Bauwesen im DIN Deutsches Institut für Normung e.V.: DIN 18195 Bauwerksabdichtungen Teil 1: Grundsätze, Definitionen, Zuordnungen der Abdichtungsarten. Beuth Verlag GmbH, Berlin December 2011
  2. Normenausschuss Bauwesen im DIN Deutsches Institut für Normung e.V.: DIN 18195 Bauwerksabdichtungen Teil 2: Stoffe. Beuth Verlag GmbH, Berlin April 2009
  3. Normenausschuss Bauwesen im DIN Deutsches Institut für Normung e.V.: DIN 18195 Bauwerksabdichtungen Teil 4: Abdichtung gegen Bodenfeuchte und nichtstauendes Sickerwasser an Bodenplatten und Wänden, Bemessung und Ausführung. Beuth Verlag GmbH, Berlin December 2011
  4. Normenausschuss Bauwesen im DIN Deutsches Institut für Normung e.V.: DIN 18195 Bauwerksabdichtungen Teil 5: Abdichtung gegen nichtdrückendes Wasser auf Deckenflächen und in Nassräumen, Bemessung und Ausführung. Beuth Verlag GmbH, Berlin December 2011
  5. Normenausschuss Bauwesen im DIN Deutsches Institut für Normung e.V.: DIN 18195 Bauwerksabdichtungen Teil 6: Abdichtung gegen von außen drückendes Wasser und aufstauendes Sickerwasser, Bemessung und Ausführung. Beuth Verlag GmbH, Berlin December 2011
  6. Normenausschuss Bauwesen im DIN Deutsches Institut für Normung e.V.: DIN 18195 Bauwerksabdichtungen Teil 9: Durchdringungen, Übergänge, An- und Abschlüsse. Beuth Verlag GmbH, Berlin December 2011
  7. Deutscher Ausschuss für Stahlbeton, DAfStb im DIN Deutsches Institut für Normung e.V.: DAfStb-Richtlinie, Wasserundurchlässige Bauwerke aus Beton (WU-Richtlinie). Beuth Verlag GmbH, Berlin November 2003
  8. Eberhard Braun, Bundesfachabteilung Bauwerksabdichtung im Hauptverband der Deutschen Bauindustrie e.V.: BWA – Richtlinie für Bauwerksabdichtung Teil 1, Technische Regeln für die Planung und Ausführung von Abdichtungen erdberührter Bauwerksflächen oberhalb des Grundwasserspiegels. Otto Elsner Verlagsgesellschaft, Dieburg 2004
  9. Herbert Ehbrecht, Bundesfachabteilung Bauwerksabdichtung im Hauptverband der Deutschen Bauindustrie e.V.: BWA – Richtlinie für Bauwerksabdichtung Teil 2, Technische Regeln für die Planung und Ausführung von Abdichtungen gegen von außen drückendes Wasser. Otto Elsner Verlagsgesellschaft, Dieburg 2006
  10. Thomas Boge and Rolf Kampen: Zement-Merkblatt Hochbau H10 – Wasserundurchlässige Betonbauwerke. Verein Deutscher Zementwerke e.V.: Düsseldorf 2010
  11. Deutsche Bauchemie e.V.: Richtlinie für die Planung und Ausführung von Abdichtungen mit kunststoffmodifizierten Bitumendickbeschichtungen (KMB) – erdgerührte Bauteile (KMB-Richtlinie), 3rd edition. Frotscher, Darmstadt May 2010
  12. Michael Bonk: Lufsky Bauwerksabdichtung, 7th edition. Vieweg+Teubner Verlag, Wiesbaden 2010

DOYMA installation instructions

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Curaflex gasket inserts

Curaline cable ducts

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DOYMA 25 Years Guarantee

As an extension to the statutory rights of the customer, DOYMA guarantees the correct functioning of your DOYMA product for 25 years from the date of its purchase. The effective date for validity is 01.01.2007. However, should the DOYMA product fail to function correctly during this time as a result of a product defect and consequential damage occurs, then DOYMA will:

  • Replace the defective DOYMA product.
  • Reimburse the required installation and removal costs following prior agreement with DOYMA up to a maximum amount of 10000 €. DOYMA reserves the right to carry out the work, which is necessary within the framework of the maximum amount, themselves or to have it carried out by a DOYMA approved third party.
  • Reimburse the cost of all property damage incurred as a consequence of the defective DOYMA product, in particular damage to your property that has been caused by the ingress of water, and repair work that has become necessary, in particular drying, painting and masonry work, following prior agreement with DOYMA, up to a maximum amount of 100000 € in each individual case, in so far as the damage was foreseeable by DOYMA; DOYMA reserves the right to carry out the work required for the rectification of the damage themselves or to have it carried out by a DOYMA approved third party.

This guarantee is only applicable when the actual DOYMA product itself is defective, and is therefore not applicable when the failure of the DOYMA product has occurred as a result of the product having been installed or used in a manner which is contrary to established engineering principles in the construction industry and particularly DOYMA application and installation guidelines; it also does not apply when the failure of the DOYMA product is related to damage to the product sustained prior to, during or post installation howsoever caused. Should you be unable to refute a substantiated objection from DOYMA, that one of the grounds for exclusion outlined here is applicable, then the rights of the guarantee will be void.

A prerequisite for making a claim under this guarantee is the submission of the original purchase invoice for the DOYMA product involved in the complaint, without this the rights contained in this guarantee are unenforceable. The original purchase invoice together with full details of the complaint must be addressed to:

DOYMA GmbH & Co
Industriestrasse 43-57
D-28876 Oyten
Fax: 0049 (0)4207 9166-199

The scope of this guarantee is restricted to the area of the European Union and Switzerland. Should you have purchased or used the DOYMA product outside the European Union or Switzerland, then this guarantee is void and you are referred to the statutory rights.

For all legal relations between DOYMA and you resulting from this guarantee agreement only the authoritative law at our registered office (German law) will apply, with the exclusion of foreign law, for the legal relations of domestic parties; the validity of the UN Convention on Contracts for the International Sale of Goods (CISG) is excluded.

For all disputes relating to this guarantee the sole place of jurisdiction will be Oyten, in the Federal Republic of Germany.

The original text can be found in German on the Internet at www.doyma.de. We cannot accept responsibility for errors made in translation.

DOYMA table of specification

Tables of sizes and tolerances

Allocations D1 [NB] > 700

Pipe/cable o/d (d) in relation to i/d (D1) of sleeve/core bore and acceptable tolerances for NB of sleeve/core bore.

Pipe/cable external
diameter d [mm]*
Sleeve/core bore internal
diameter D1 [NB in mm]
Tolerance Pipe sleeve external
diameter D2 [mm]
Ø- min D1 Ø- max D1
1 – 24 50** 49 53
1 – 40 80 78.5 83 140
41 – 57 100 98.5 104 160
58 – 77 125 123.5 128 165
78 – 104 150 148.5 153 190
105 – 145 200 199 204 245
146 – 190 250 247 253 300
191 – 233 300 297 304 350
234 – 288 350 347 354 400
289 – 339 400 397 404 470
340 – 380 450 447 454 520
381 – 430 500 497 503 570
431 – 530 600 597 603 680
531 – 620 700 697 703 800
621 – 720 800 797 803 894
721 – 820 900 897 903 1004
821 – 920 1000 997 1003 1114
921 – 1020 1100 1096 1102 1226
1021 – 1110 1200 1196 1202 1338
1066 – 1210 1300 1296 1302 1448
1211 – 1310 1400 1396 1402 1564

* In case of order the exact outer diameter of pipe/cable is required because there are different gasket inserts to seal the pipes – see table below.

** Gaskets for NB 50 only available for core bores or pipe sleeves already installed.

 

Gasket Insert Diameter table of specification

NB of sleeve/core bore according to external diameter of service d.

NB (D1) Ø- of service (d) [mm]
50 1 – 6
7 – 12
13 – 18
19 – 24
80 1 – 6
7 – 13
14 – 21
22 – 28
29 – 35
36 – 40
100 41 – 45
46 – 52
53 – 57
125 58 – 67
68 – 77
150 78 – 85
86 – 94
95 – 104
200 105 – 115
116 – 124
125 – 135
136 – 145
250 146 – 156
157 – 165
166 – 172
173 – 179
180 – 186
187 – 190
NB (D1) Ø- of service (d) [mm]
300 191 – 197
198 – 207
208 – 215
216 – 224
225 – 233
350 234 – 240
241 – 249
250 – 259
260 – 269
270 -278
279 -288
400 289-294
295-300
301-306
307-311
312-317
318-322
323-327
328-333
334-339
450 340-344
345-350
351-356
357-362
363-368
369-370
371-375
376-380
NB (D1) Ø- of service (d) [mm]
500 381-386
387-392
393-397
398-403
404-409
410-415
416-420
421-425
426-430

 

Subject to technical alteration without notice

Attention!
For pipes > NB 500 part numbers do not exist. Please furnish particulars/advise exact measurements.

London Underground, Victoria Station Upgrade

Client: Transport for London
Main Contractor: Taylor Woodrow/BAM-JV
Year: 2012
Value: £40,000

LondonUnderground01

Overview:

This phase of the Victoria Station upgrade involved the electrical installation between the North Ticket Hall and South Ticket Hall, whilst keeping the station operational. Mott McDonald had designed the power and communication cable network to follow a route to the external of the station building, under adjacent roads and into each ticket hall. This formed the most practical way of connecting both ticket halls effectively, but required an effective watertight sealing system that ensured the vital network cables were protected.

LondonUnderground02

Solution:

Mott McDonald approved the installation of Interflow UK Ltd’s DOYMA Service Duct Sealing system on the project. As the service ducts needed to be installed through the walls of both the North and South Ticket hall, it was vital that there was no risk of water penetration at the joints of wall, duct and cable, particularly in light of a high water table within the vicinity. The fact that Interflow UK Ltd installed and supplied a product in one package was vital to the solution. The DOYMA system of high density EPDM, within a steel gasket, ensured that the cable network was protected from both water and gas infiltration. This was supported in the design, manufacture and installation by Interflow of two bespoke penetration plates as required by the specification. As an additional fail safe, new tanking was installed over the top of the connection.

Why Interflow Were Used:

Key to the success of this package was that Interflow UK Ltd installed the DOYMA System on site, using their skilled installation team, whilst being the appointed UK supplier of the DOYMA system. Additionally, a 25 year insurance backed product guarantee was supplied. Moreover, the DOYMA system was quicker to install than considered alternatives, enabling the programme to stay ahead of schedule and minimising disruption to road users in the area.

“We chose The DOYMA System through Interflow because it was a tried and tested system, but also it was a plug and play solution. All the installation was very speedy by Interflow and resolved all our concerns regarding water tightness and programme.”
Palan Senthor-Mott McDonald.

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