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PMT architects, designers and historic buildings consultants

Century Buildings 31 North John Street Liverpool L2 6RG Tel +44(0)151 239 1600 www.pmt.co.uk

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Principals Mark Goldspink James Coath Michael Morrison John Burton Jane Kennedy Andrew Clark Martin Stancliffe Chris Betts David Bissonnet Brian Anderson Nigel Sunter Mark Hammond Geoffrey Holland Richard Putnam Richard Ellis Ian Alderton Associates Simon Marks Denis Butler Dante Vanoli Peter Gooderham Mike Rudd John Rutherford Matthew Hollingsworth Carl Andrews Christopher Cotton Ulrike Knox Oliver Caroe Paul Prentice Stephen Elliott Purcell Miller Tritton LLP is a limited liability partnership registered in England and Wales registered number OC315259. Registered office 3 Colegate, Norwich, Norfolk NR3 1BN

Outline Condition Survey for Burton Manor Walled Garden First Draft

Purcell Miller Tritton, Century Buildings, 31 North John Street, Liverpool L2 6RG Page 1 of 19

Contents 1.0 Introduction

1.1 The Brief

1.2 Scope of the report

2.0 Brief Description 2.1 The Walls

2.2 The Northern Glasshouse

2.3 The Southern Glasshouse

3.0 Observations and Recommendations 3.1 The Walls



Appendix A Key Plan

Appendix B Schedule of photographs



1.0 Introduction

1.1 The brief

The brief for the survey was issued by 20/20 on 19th September 2006.

1.2 Scope of the Report

This condition survey was carried out by Purcell Miller Tritton LLP during September and October 2006. As part

of this scope Capstone Consulting Engineers Ltd were instructed by Purcell Miller Tritton LLP to undertake a

Structural Appraisal on the walled garden. The survey covered the wall highlighted in bold on the attached key

plan, to include the external/north elevations of the Nursery and Reading Room, and of the two glasshouses

(labeled ‘1’ and ‘2’). A site visit was made on the 26th September 2006, and observations made from ground

level. The walls and two glasshouses were viewed from all accessible areas. In places dense vegetation,

buildings or lack of safe access restricted the inspection. No detailed timber inspection, ‘opening up’ works or

close-to inspection at height were undertaken.

This outline condition survey concentrated on the general condition and structural engineering issues only.

Hence detailed descriptions of the structures surveyed and minor or non structural deterioration or defects were

not recorded. This appraisal is not intended to be a specification for remedial work.

It is intended that this condition survey be read in conjunction with the key plan and the schedule of

photographs found in Appendix A and B respectively.

2.0 Brief Description

2.1 The Walls

The walls (shown in bold on the key plan) are constructed in a mixture of brickwork and sandstone. Generally

they are free standing, without buttresses, and made up of solid brickwork laid on lime mortar in a four course

English Bond pattern (being four rows of stretcher bricks followed by a row of header bricks) built off a ‘plinth’ of

large soft and weathered sandstone ashlars. This plinth is typically flush with the wall. In places the wall acts as

an earth retaining wall as the ground level on one side lower than the other.

The fee standing walls to the south east are wider at their base, being two bricks thick, reducing in thickness at

a low level (in some instances it can be seen that this occurs below ground level) to one and a half bricks. The

wall steps in again at high level to a brick thick, and is topped with a sandstone coping. The run of wall to the

south east is generally c.2.9m tall.

The northern wall to the west of the Reading Room is generally taller, and tends to contain more sandstone



ashlars (or possibly coursed rubble: they are typically so weathered it is not clear) and less brickwork. This also

reduces in thickness with height.

The northern wall to the east of the Reading Room differs again. This wall is more predominantly brick, on a

sandstone plinth. At high level the inside face of the wall corbels outwards to meet the glasshouse roof. Hence

the wall and the lean-to structure provide mutual support to each other. Without the roof to prop the wall, the

corbelling would be a destabilising weight on the wall. There are a series of regularly spaced cast iron pattress

plates on the north elevation of this section of the wall at high level. These are anchorages points tying the

northern lean-to glasshouse to the wall.

The piers are formed in large blocks below a capital topped with a ball. The timber gates across the vehicular

access are open, and the pedestrian gates flanking these are shut and not in use.


The northern glasshouse (ref glasshouse ‘1’ on the key plan) is a lean-to glasshouse built on the south

elevation of the northern wall. It consists of 5 bays, separated with glazed partitions. It is likely that the eastern

two bays are a later addition. The eastern most bay contains a brickwork gardener’s office. A low glazed timber

framed wall runs along the south side of the glasshouse, bearing onto a brickwork plinth. Trussed timber rafters

at c.5’ ccs span from this wall to the high northern brickwork wall. These trussed rafters consist of a timber

compressive member with an iron tie member held below via short cast iron strut (forming an inverted king post

truss). Small ‘T’ section iron purlins span between these trussed rafters and provide a mid span support to the

regular timber rafters in between the trussed rafters. At regular intervals an iron tie bar runs up from the top of

the southern brick plinth to the northern wall. It is likely that it is these tie bars that are anchored back to the wall

via the pattress plates observed externally.

As noted in 2.1 above, the rear wall to the glasshouse corbels inwards to meet the roof. Hence the wall and the

lean-to structure mutually support each other.


The southern glasshouse (ref glasshouse ‘2’ on the key plan) is a free standing glasshouse with a duo-pitched

roof. The structural form shares many similarities with that of the northern glasshouse. Again, this glasshouse is

split into a series of bays. A low brickwork plinth supports the glazed timber framed elevations. At c.5’ ccs the

structural frame is ‘portalised’ (stiffened) at the connection of the posts to the rafters above via a cast iron

haunch moulding. This moulding continues down as the vertical post to the frame and is inset from the timber

elevation. It bears onto the brickwork plinth.

Small ‘T’ section iron purlins span between the principal rafters forming these frames, offering mid span support

to the regular rafters in between. Alternate pairs of principal rafters are supported at the apex of the roof by a

cast iron column (ie the columns are at c.10’ ccs). These columns also support a pair of ridge beams. The ridge



beams in turn support the apex end of the regular rafters and the intermediate principal rafters (ie those without

a cast iron column).

The west end of the glasshouse is asymmetrical. Steps lead down to a boiler room either below the glasshouse

or to one side (not accessed). Against this, a tall brickwork wall raises the eaves level of the north elevation

considerably in relation to the lower south elevation. The asymmetrical cross section leads to a different

structure. Iron scissor-bracing ties ‘truss up’ the principal rafters. These trusses support the ridge beams. There

are no internal cast iron columns to this half of the glasshouse, and the remainder of the roof structure

hierarchy remains similar to the east end.

3.0 Observations and Recommendations

Approximate Costs (£)

Priority Priority Priority

3.1 The Walls 1 2 3

Location ‘A’:

On the east side at low level the sandstone is extensively eroded just below

the brickwork. This loss of material has ‘undermined’ the brickwork by

around 45mm. The wall is thick at its base, and this undermining is unlikely

to represent more than 10% of the wall thickness. None the less this will be

weakening the wall. It is likely that the erosion is greatest at the interface

with the brickwork as rainwater running off the brickwork is concentrated

here.

On the west side there are recessed joints to the brickwork. These

weathered joints are contributing to the reduction in cross section of the wall

at this location.

It is recommended that the sandstone be repaired by cutting in new

work to replace that eroded. The new sandstone should be fully packed up off the brickwork above ensuring the brickwork is fully

supported. Consideration ought to be given to the introduction of a

form of drip/sill detail to shed water from the brickwork off the wall away from the sandstone below.

There is some hair line cracking to the hard cement repointing around the

soft brickwork at high level.

Consideration should be given to removal of the hard cement mortar in



all locations where it occurs on this wall, replacing with a hydraulic

lime mortar.

Location ‘B’:

The voussoirs forming the arched opening at this location have open joints

due to the weathering of the mortar. This will be weakening the arch slightly,

and if left unchecked may eventually lead to movement to the arch.

It is recommended that the open joints be repointed.

To the south west of the archway there is a sandstone block that appears to

have been damaged by vehicular impact.

It is recommended that this stone be repaired and rebedded.

Location ‘C’:

The wall dog-legs in plan behind a late twentieth century flat roofed garage.

On the south side behind the garage, deep open joints were noted towards

the top of the wall. In the same location on the north side of the wall

cracking was noted to the brickwork at high level, along with vertical open

joints over its height at the corners. It is possible that the cracking relates to

minor thermal movement along the two longer lengths of wall, causing slight

rotation in plan of the shorter joining wall.

It is recommended that the open joints be repointed and that

consideration be given to installing stainless steel bedjoint

reinforcement into the wall forming the dog leg in the region of the

cracking.

A tree is growing close to the north side of the wall at this location.

Whilst distortion to the wall was not observed, in the long term leaving

the tree in place may lead to movement to the wall and consideration

should be given to the removal of the tree.

Location ‘D’:



The brickwork slightly ‘overhangs’ the sandstone below in a similar manner

to location ‘A’. This is because the upper sandstone blocks are weathering

back in relation to the brickwork above.


work to replace that eroded. The new sandstone should be fully

packed up off the brickwork above ensuring the brickwork is fully supported. Consideration ought to be given to the introduction of a

form of drip/sill detail to shed water from the brickwork off the wall

away from the sandstone below.

Location ‘E’:

There is a small area of loose brickwork adjacent to the arched opening

through the wall at this location. Where the wall returns to the adjacent

house, it also steps up in height. The brickwork at the face of this step also

appears to be loose from ground level.

It is recommended that all loose work be rebedded and any open joints

be repointed. Consideration should be given to introducing stainless

steel bedjoint reinforcement to the loose high level work.

Location ‘F’:

This is the location where the wall meets the east end of the lean-to green

house, providing mutual support (ref the description). The brickwork at the

face of the step up in the wall at this location appears to be loose from

ground level. There is also a slight outward (northern) lean at high level

where the brickwork curves round to the north elevation.

It is recommended that all loose work be rebedded and any open joints

be repointed. Consideration should be given to introducing stainless

steel bedjoint reinforcement to the loose high level work, and along the bedjoints of the leaning section, anchoring it back to the plumb

work on either side.

The pattress plates at high level to the west of location ‘F’ are rusting.

Whilst cast iron is far better at resisting rust than wrought iron or mild



steel, it is recommended that they be derusted and repainted to protect

them from this ongoing deterioration. It is likely that the mortar

bedding the plates to the wall will also need to be renewed, protecting

the tie bar within.

A section of brickwork at high level to the west of ‘F’ is bulging. This bulge

occurs above a particular bedjoint, creating a step from the plumb work to

the bulged work above. The step is in the order of c.10-30mm. It is likely that

this bulge is the result of thermal movement, causing the brickwork to buckle

in the horizontal plane.

It is recommended that consideration be given to either rebuilding this

section of wall at high level or introducing bedjoint reinforcement to secure

the bulged work back to the work on either side.

Reading Room North Elevation:

There are a number of open joints to the cornice stones. These will be

letting water into the masonry. The flashing to the flat roofed extension to

the Reading Room (on the west side) appears to be failing, again allowing

water into the masonry. It is likely that this roof has timber joists and these

may be decaying as a result of water penetration through the roof and

flashings. The gutter and down pipes also appear to be failing, allowing

water to penetrate into the masonry.

It is recommended that the open joints be repointed and consideration given to flashing over these horizontal surfaces vulnerable to rain

water penetration. The guttering and roof finishes should be assessed

in detail and renewed. It is recommended that timber work be

assessed for decay when it is accessible at that time.

There are signs of past and recent (possibly ongoing) movement to the

Reading Room flat roofed extension, where it joins to the wall. There is a

wide vertical band of cement repointing between the Reading Room stone

work and the wall. This repointed work has a vertical crack running up it,

indicating further minor movement since the repointing was added. The

repointing and crack indicate that the reading room itself may have moved in

relation to the brickwork. Roots from an adjacent tree can be seen hard up

against the Reading Room extension exterior at the pavement level.



On the inside (southern) face in this location it can be seen that the

brickwork wall has been rebuilt in recent years and is distorted and out of

plumb (leaning towards the north). It is not clear whether these distortions

are inbuilt or are the result of movement since that time.

Further investigations would be required to determine the cause of this movement, but it is likely that it relates to foundation movement of

the reading room extension. This was added to the reading room in the

past and it is likely that it has shallower foundations. It is possible that

the adjacent tree or a failing drain may be contributing to this

movement, altering the moisture levels and hence possibly the

characteristics of the supporting ground.

In the interim it is recommended that the crack be repointed and

consideration be given to tying the reading room masonry to the

brickwork wall with bedjoint reinforcement.

On the north elevation of the wall to the west of the Reading Room, large

cement patches have been installed over extensively weathered/eroded

sandstone blocks below the brickwork. These well meaning repairs can

result in further and even accelerated deterioration of the sandstone.

It is recommended that the cement be removed and that the sandstone

be repaired by cutting in new work to replace that eroded. The

sandstone should be fully packed up off the brickwork above ensuring the brickwork is fully supported. Consideration ought to be given to

the introduction of a form of drip/sill detail to shed water from the

brickwork off the wall away from the sandstone below.

Location ‘G’:

The north side of this wall abuts the main road through the village. As seen

in other locations (‘A’ and ‘D’), the lower courses of sandstone are

weathered and eroded back in relation to the brickwork above, particularly at

the junction with the brickwork. At ‘G’ there is white coloured lichen growing

on the sandstone along the wall in this location.





packed up off the brickwork above ensuring the brickwork is fully

supported. Consideration ought to be given to the introduction of a

form of drip/sill detail to shed water from the brickwork off the wall

away from the sandstone below.

There are also deep recesses to the sandstone mortar joints along the wall

in this area. In one location an open joint passes right through the wall.

It is recommended that all open and deeply recessed joints be

repointed in a hydraulic lime mortar.

Nursery North Elevation:

On this gable to the Nursery the lower two courses of sandstone are very

weathered and eroded back in relation to the work above, weakening the

wall. It is likely that this erosion relates to water run off from the road,

running along the wall, and from splash back of rainwater hitting the road.



packed up off the work above. Consideration should be given to

improving the drainage along the north side of the road, should a

detailed assessment show this is the cause of the erosion.

Location ‘H’:

The capital of the eastern most pillar built into the northern wall has moved.

It is possible that this was caused by vehicle impact.

It is recommended that the capital be rebedded and doweled back onto

the pillar below.

There are open joints to the eastern pillar to the double gated vehicular

entrance. The pattern of these joints indicates that the pillar has moved to

the west away from the lintel over the pedestrian entrance. It is likely that

this movement has been caused by the weight of the hung timber gate. The

gates do not appear to have been used in recent years and are currently

supported in the open position.



It is recommended that the open joints be repointed. Should the gates

be reinstated and used, then consideration should be given to

strengthening the pillar to resist further movement.

Movement has occurred between the southern most pillar, and the

terminating wall connecting to it. Stepped vertical cracking/open joints are

visible on the west side of the wall adjacent to the pillar. It is likely that this

movement relates to differential movement between the pillar and wall

foundations.

It is recommended that bedjoint reinforcement be installed between

the pillar and wall to improve the tie between the two, and that the

open joints be repointed in a hydraulic mortar.

In a number of locations spawling of the sandstone was noted to pillars

where rusting iron work is embedded into them, being either internal cramps

or the gate pins. In some cases the stonework above has been lifted by the

expanded metal. The worst case of spawling is to the top pin on the

southern most pillar (note the gate has been removed), and the large stone

holding this pin has a split across its entire length. In other locations sizable

pieces of sandstone have been lost or are loosely held in place.

It is recommended that all ferrous iron work be removed from these

pillars, including the gate pins. Dowels and pins can be replaced in

non-ferrous metal that will not rust, expand and cause further damage. It is likely that some rebuilding and stone replacement will be

necessary.


The glasshouse is in a state of disrepair. Typically gazing panes are

missing, allowing water to stand on unprotected timber. The paintwork to the

timber has failed generally, and in many locations the timber is weathered

from exposure to the rain. Decay has typically occurred at connections

where the water has been able to penetrate into the timber, leading to a

number of localised collapses. Cast iron and other iron elements (wrought or

mild steel) are rusted. A number of the cast iron elements are broken. The

low level brick plinths are generally in a poor condition with loose brickwork

and open joints. Self seeding vegetation is growing in the glasshouse, and



in locations up through the roof structure.

Considering the five bays in turn, working from east to west:

1st bay: this is partially glazed. The structure is on the whole intact.

2nd bay: a principal rafter has collapsed, causing the supported rafters either

side to also collapse.

3rd bay: the masonry plinth to the separating wall with the 4th bay has

collapsed.

4th bay: the roof is extensively collapsed. The masonry plinth has collapsed.

A mature tree is growing up through the plinth location. The masonry plinth

to the separating wall with the 5th bay is severely distorted.

5th bay: the roof is extensively collapsed. A mature tree is growing up

through the plinth location and the plinth is severely distorted in places. The

internal brickwork wall to the office is distorted as a result of decay to the

timber lintel supporting it.

The following recommendations are given assuming that it is the

intention to repair and restore the glasshouse back into a state of

good repair:

It is recommended that the structure be made safe with temporary supports, allowing the vegetation and collapsed sections to be

removed. The brickwork plinth will need to be repaired where distorted

and rebuilt where missing. A detailed assessment of the timber will

allow a replacement schedule to be drawn up. Given the fact that the

timber sections are slight, it is likely that replacement rather than

repair will be more appropriate for decayed timbers. Existing metal

elements can be used to create accurate duplicates to replace those missing or broken.


The glasshouse is also in a state of disrepair, but has not suffered the roof

collapses seen on the northern glasshouse. Typically gazing panes are

missing, allowing water to stand on unprotected timber. The paintwork to the



timber has failed generally, and in many locations the timber is weathered

from exposure to the rain. Decay has typically occurred at connections

where the water has been able to penetrate into the timber, leading to a

number of localised collapses. Cast iron and other iron elements (wrought or

mild steel) are rusted. A number of the cast iron elements are broken,

including columns (splits and through rusting seen).

The low level brick plinths are generally in a poor condition with loose

brickwork and open joints. The brick plinth has been dismantled at the east

end, and the timber work above propped off timber posts. Self seeding

vegetation is growing in the glasshouse. Sizable trees are growing up

through the roof structure.

The roof over the steps down to the boiler room has collapsed.

The following recommendations are given assuming that it is the

intention to repair and restore the glasshouse back into a state of

good repair:

It is recommended that the structure be made safe with temporary

supports, allowing the vegetation and any sections found to be

collapsed to be removed. The brickwork plinth will need to be repaired

where distorted and rebuilt where missing. A detailed assessment of

the timber will allow a replacement schedule to be drawn up. Given the

fact that the timber sections are slight, it is likely that replacement

rather than repair will be more appropriate for decayed timbers. Existing metal elements can be used to create accurate duplicates to

replace those missing or broken, which will include a number of cast

iron columns (mild steel circular hollow sections would be a sensible

replacement option here).



APPENDIX A



APPENDIX B

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