Case Study 2

Overview

I understand this is a New Build Development of 8 Flats, 2 flats on each of the four levels, the project is being built under Pre-completion Testing procedures within Approved Document E. The client has asked us to review the drawings and recommend treatments as required. Please see General Arrangement below

This is a very simplified representation of the layout, it is not to scale and should only be used for reference purposes.

Brief

We have been asked by the client to carry out a drawing review, in order that we can assess the suitability of the new proposed construction methods, to meet Approved Document E. The client has problems with the fitting of the concrete floor planks and now needs to reassess the suitability of the whole construction in relation to meeting the regulations.

Approved Document E Requirements

Under A.D.E. you are required to insulate between residential dwellings / flats and other flats or commercial properties.

Therefore within this development there are 3 Separating Floor levels that will need testing and 4 Party Walls that may need testing.

In a strict assessment of the situation the development falls in with in the New Build scope of Approved Document E of the Building Regs and as such should meet the standard criterion as detailed below.

Flat New Build Separating Floors

Separating Floor Between Flats Airborne Noise Reduction = 45dB Dn T,w + (Ctr) or greater

Separating Floor Between Flats Impact Noise Reduction = 62dB Ln T,w or less

Flat New Build Separating Walls

Separating Wall Between Flats Airborne Noise Reduction = 45dB Dn T,w + (Ctr) or greater

Please Note, we are not allowed to test hallways under current guidelines however we are allowed to test to bathrooms provided there are no other alternatives

It is important that when choosing construction methods of Party Floors and Walls that you try to keep all construction methods the same as this will reduce the numbers of tests required and therefore keep costs down.

Bearing this in mind if all constructions are the same then the numbers of tests required here would be as follows:

2 No. Separating Floor Airborne Noise Reduction Tests = 45dB Dn T,w + (Ctr) or greater

2 No. Separating Floor Impact Noise Reduction Tests = 62dB Ln T,w or less

There is only one place on each level where the Party Wall can be tested in this development:

2 No. Separating Wall Airborne Noise Reduction Tests = 45dB Dn T,w + (Ctr) or greater

It would be prudent to check this with Building Control on receipt of this report so that they can verify this to save any confusion at completion stage.

Current Status

I understand that this project is now at build stage and the client is up to 2nd Floor level, we can not get any exact details on the materials used in the construction however we believe construction being used is a medium density concrete block inner leaf wall with a concrete plank type floor 200mm thick, sitting on the inner leaf, we understand that the planks were laid dry onto the block walls without using the recommended a mortar mix. The client has made sure that there are no walls running continuous through more than one, this provides an acoustic break of continuity and will therefore help sound insulation.

There are various steel beams within the project on each level, these are set into the floor as well as into the walls at floor level.

I have reviewed the drawings and checked various construction issues relating to Approved Document E, the main issues are listed under the headings shown below.

• External Walls
• Party Floors between all levels
• Party walls between Flats and communal areas
• Internal walls / partitions
• Additional Flanking routes ie steel work
• Treatment of stairs and communal staircases.
• Bathroom Fitting Detail
• Recessed Lighting
• Final fitting check list
• Final Summary

Please see below for each area under consideration and recommended treatment

1.External Walls

We understand that the external walls consist of a 100mm thick inner leaf 100mm typical void and normal brick outer skin. These inner leaf block walls then support the concrete planks, we believe the density of these blocks are1350kg/m3 for 110mm thick blocks and 1990kg/m3 for 140mm thick blocks.

I also understand that the architect requires these external walls to be lined with an insulated plasterboard 40-50mm thick, I would recommend that the wall be rendered before applying the insulated plasterboard. The wall must also first be pointed to ensure all gaps are filled, you should also ensure that you fill in joint between top of block walls and underside of plank floors. Please see sketch below

Party Floors between All Levels

The Party Floor construction comprises mainly of a 150mm thick concrete Bison Plank floor, a thick screed and floating floor finish is required above, whilst below the intention is to install a Metal frame suspended ceiling. Unfortunately the Bison Plank floor has not been calculated correctly and there are many large gaps between some of the planks on each level. This now means that it is going to be very difficult if not impossible to get this floor to work acoustically in the manner it was designed.

From above the intention was to install a floating screed and then to build up the internal walls, however some of these internal walls have now been erected making it impossible to install a floating screed. This will also affect the performance of the whole construction as we may well get Flanking noise travelling down the internal walls into the plank floors.

I therefore suggest that we change the construction to help compensate for these issues, however extreme care must be taken to ensure the work is carried out as advised.

From Above

I would suggest that, first you should back fill all the gaps in the concrete floor using shuttering ply underneath and pouring in a dense concrete mix (approx 2000kg/m3) so that all crevices are filled. You should then add a min 60mm screed (mass approx 80kg/m2) on top of the existing plank floors, you can then finish building all the internal walls down on to the sub-floor. Once the walls have been insulated and plastered as per spec in section 4 of this report. A floating floor can then be added into each room, however the floating floor must not be run from room to room, instead you should ensure that you fit the isolation tape between different areas of flooring.

From below

I would suggest that all exposed steel work is packed with Rockwool held in place with chicken wire mesh. Ensure that the joint between inner leaf block walls and concrete planks have been filled. You should then install a suspended MF Ceiling creating a 150mm void with 50mm light weight insulation Roll, 2 layers of 15mm SoundBloc plasterboard could then be fixed to the underside of the joists.

Please see diagram above for floor build up including materials required

Important points

• Ensure that all gaps in the concrete plank floor are filled with wet mortar from below.
• Ensure that you encase any exposed steel with Rockwool as shown above.
• Ensure that you use special Acoustic Hangers for the Metal Frame Ceiling frame
• Ensure that these Acoustic Hangers are fitted exactly to manufacturers specifications
• Ensure that only Acoustic and Fire Rated Down Lighters are used.
• Ensure that you do not fit them to close together (see manufacturers specifications)
• Ensure that you do not fit too many in any one room (see man. Specifications)
• Ensure that the wall is lined with insulated plasterboard AFTER ceiling has been installed.
• Seal all gaps between sheets of plasterboard
• Ensure plasterboard is stagger fixed.
• Ensure all perimeter joints on wall and ceiling are sealed with silicon or mastic.

Floor build up closer detail

Important points

• Ensure that Regupol joints are overlapped and taped as per manufacturers instructions
• i)Ensure that the flanking Tape returns onto the hardwood flooring
• i)Ensure that the skirting boards sit onto the Flanking Tape.
• i)Ensure that the timber Battens ARE NOT screwed into concrete screed.
• i)Ensure that all steels in walls at floor level are encased in concrete prior to laying Regupol.
• i)Ensure that Hardwood floor DOES NOT contact any skirting, door treads or door frames.

Specific Materials

• 1.Regupol 4515 Multi purpose Rolls 18m x 1m x 4.5mm @ £7.90 per m2 + Vat
• 1.Regupol Adhesive 15 Ltr Tub (coverage 35-40m2) @ £ 39.75 per Tub + Vat
• 1.50mm Thick 45kg/m3 Rockwool Slab @ £3.35 per m2 + Vat
• 1.50mm Thick apr1200 Insulation Roll @ £2.75 per m2 + Vat
• 1.15mm SoundBloc Plasterboard 2.4m x 1.2m x 15mm @ £2.55 per m2 + Vat

3.Party Walls between Flats and Communal areas

There are 2 types of Party Wall constructions in this development:

• Flat to Communal Area Separation = 2 Courses of 110/140mm Concrete Block 75mm cavity
• Flat to Flat Separation = 2 Courses of 110 mm concrete Block 75mm cavity

The density of these blocks is 1350kg/m3 for 110mm thick and 1990kg/m3 for 140mm thick blocks, provided these walls are rendered and then plastered then this should be sufficient, do not apply Dot and Dab plasterboard to these walls. Do not penetrate these walls with services.

Internal Walls / Partitions

There is no requirement here except for the standard Rw 40 dB Wall that would normally consist of a 4” x 2” stud and a single layer of plasterboard with 50mm 10Kg/m3 Insulation, I understand you will be using a lightweight metal frame studwork, this has been fixed down onto the subfloor already however providing the screed is then laid as a continuous layer directly onto the floor slab then this should be ok. You must finish insulating and lining all internal stud work before you lay the Regupol underlay.

Additional Flanking routes ie Steel Beams etc

In developments such as these, there are always other routes that the sound will try to take during the test, the common Flanking routes are:

• Steel beams
• Service pipe work running through Party Floor
• Electric Sockets in Separating walls

Steel Beams

There are many steel beams in this development although they are all either in the walls or in the floor, these are a concern and they will require treatment to try and reduce flanking.

I have given below a few examples of steels within the building and how they should be Treated.

Treatment of steel inset in floor

Treatment of Steel inset in wall at floor level

Service pipe work runs

I understand that all services will be taken down the wall on each level so there will need to be treatment of these areas, please see plan view of suitable treatment below:

Electric Sockets in Separating walls

Under Approved Document E guidelines you are advised not to put sockets in both sides of a Party Wall, as sound will try to break through at these points.

Treatment of Stairs

Where a communal staircase is located directly above another Flat, then this should also be treated, however it will not require testing. There is a standard detail within Approved Document E. with regard to this situation. Please see below.

In this case we will not have to insulate the underside of the stairs, as it should not ever be above another flat, however you will still have to provide impact noise reduction by using impact reduction mats as shown below.

Impact Mats 1.2m x 1.2m x 12mm Cost £22.50 per m2 + Vat

There is also a small section within Approved Document E that advises you to reduce reverberation with in communal staircases, this is especially true in concrete staircase situations as they hard flat surfaces will all reflect sound and therefore increase the echo effect (reverberation). To treat the communal stairway in your case it is important that as many of the surfaces as possible, within this area are covered with an absorptive material. The most obvious of these is a good thick carpet and underlay, but you will also need absorptive ceiling tiles. There are several manufacturers of these tiles, we will provide assistance in sourcing a suitable product if requested.

Bathroom Fittings

When installing sinks and toilets or indeed shower trays into rooms where acoustic floors are being installed then the flooring is the last thing to be added, you must never fit toilets etc onto floating floors as the movement that will naturally occur may damage tiles or joints.

Instead you should create a plinth for each item, the thickness of the floating floor and fix it directly to the original floor surface, you can then place the flooring up against these plinths using the Isolation tape as a seal. Please see fig 7 below.

Down Lighters

As I mentioned earlier in the report and on site, down lighters or recessed lights are not recommended for this type of floor construction as they may severely affect the acoustic performance of the floor structure, indeed you fit these entirely at your own risk. However if you must use them I would recommend that you use Acoustic Downlighters such as found at the following website address

http://www.tlc-direct.co.uk/Main_Index/Security_Menu_Index/Fire_and_Smoke/Fire_Rated_Downlights_Lv/index.html

You must however fit these exactly to manufacturers specifications, holes cut over size and too many lights per room will seriously affect their performance.

Finishing detail check list

I have produced the check list attached for your convenience to ensure that you cover all the major points normally missed during installation, some of the points may not apply to you but most will so please read and follow carefully, if there is a problem with the actual test we will need to know whether these things have been done correctly.

Final Summary

I have detailed the above treatments as best as I can based on the drawings and flat layouts provided, however I would respectfully suggest that you arrange a site visit once the roof structure is in place, so that we can check the actual construction on site.

I trust the above is acceptable but if you have any questions regarding the above then please call me on the numbers above, I look forward to hearing from you in regard to supply of the materials suggested and I remain

Yours sincerely

Mark Page A.M.I.O.A. (Associate Member of the Institute Of Acoustics)