St Hugh s Charterhouse

Transcription

1 St Hugh s Charterhouse Cross (wheeled head or Celtic) 26.3m from parapet Figure 1 1

2 Below top 4.1m at the 7m, 12m, 17.2m 20m, and 24m levels corbel or ring stone work is formed in a decorative fashion, between which coursed infill sections are built in situ, to create the multi layer effect. Rolled quadrangle sections are built in to 8no. sides vertically to create the spire s 8 faces. Small apertures are present to 4.1 m level, a foil is located at the 7m levels and below this at the 17.2 to 20m levels lancet windows are present with hood moulding. At lower level at balustrade or parapet level a clock face to 2 number elevations is presently situated. Solid stone 4.1m No1 Apex 700mm No2 400mm No3 400mm Stone type presumed BATH Figure 2 2

3 St Hugh s Charterhouse, Horsham, RH13 8EB Spire Laddered Examination Date Inspection date 29 th June Brief Carry out an examination of the Spire external faces using temporary access ladders and rope access rigging - from Tower Parapet up to the Apex checking for possible causes of weather ingress. Submit report with digital photographs of conditions encountered. Report Spire Apex Masonry and metal finial cross appear generally sound. Upper 1.5m courses of masonry appear generally sound. Face-work shows gradual weathering erosion. Solid Stone 2.3m level to 4.1m As digital photographs will show fissures were encountered on West elevation running through masonry to South west elevation, vertically and horizontally, extending around and through rolled quadrangle details, see photograph Also northeast elevation is showing similar conditions, highlighted in photograph 051 & to 26.3M below Spire Apex There is weathering related defects apparent: a. Stone face work shows degrees of erosion, with differing masonry beds showing perforated and scaling or exfoliated surfaces, depending upon variations occurring in the source or laying of the stonework during construction. b. Holes are evident into/through the masonry of spire wall. c. Original lime mortar shows both gradual erosion and significant voids/vents. Repointing, in various mixes and generally thinly applied, has been carried out but is now exhausted, some cementitious, Planned removal/conservation of the remaining loosening stonework is essential. Slate louvres are in good condition. Base of Spire Shows relatively good conditions, with minor works to fill voids and weathered bed joints. 3

4 Lightning Conductor System Franklin Rod type system and predates the current BS6651/1999. The single copper down conductor is bonded to finial cross and internally to base of vane-post (unseen) and passes down the steeple to earth. There are several (unwelcome) joints and atrophied material. A second down conductor has been added to complete a more comprehensive system of 8mm aluminum PVC covered connected with a bi-metallic joint, this seems in good order, and a second conductor of this type should be fitted whilst the opportunity of access is in situ. Electrical testing of the earth resistance gave a result of no reading obtained to existing original and disconnected 8.0 Ohms to more recent addition. Overall condition is UNSATISFACTORY. Test Certificate cannot currently be issued. Internal evidence of weathering walking up access to internal levels, following previous rainfall. Revealed very damp areas, water and driving weather conditions are allowing penetration into inner spire. King Post The existing king post is approximately 4m in length terminating internal to a sectional cross section stainless steel turned bracket, this seems to be an alteration, and the original king post projected further down internally. The alteration may account for the stress fissures encountered externally, as an alteration of king post length may affect wind load and capacity of the spire to deal with wind deflection. Also natural expansion may be restricted by the alteration, we would recommend reinstating originally specified configuration. The cross section internal bracket is fixed with non standard fixings, i.e. not approved materials not non ferrous (shows rusting to fixings.) Photograph 001. Digital Photographs ( accompany this report) Further to reading and digesting this report with accompanying photographic evidence of defects encountered, please contact us to discuss any matters arising. The ladders and associated rigging have been left in situ; to save the costs of rerigging for the essential Make safe and conservation works. Consider Budget Quotations 1. Carry out Make Safe Works De-scale loose masonry face work, and similarly carefully remove spalling masonry to the full external face of the Spire, Prepare, lime mortar fill in stages, and re-point the masonry stonework and joint voids/vents to external face. 4

5 2. Stitch pin with stainless steel mm dowels loose masonry to top 4.1m in areas showing fissures. 3. Spire Conservation Prepare to approved depth and carefully re-point all weathered open joints and voids of external spire faces, using lime mortar to English Heritage standards. 4. Upgrade Steeple Lightning Conductor to BS6651/1999 Install a second down conductor, connect to coronal conductor at parapet level, all interconnected to the existing equipment, forming a Faraday Cage type lightning conductor system, with a second and new earth termination at ground level. 5. King post Extend existing king post with interconnected stainless steel rod to cross tree or original fixing detail. These are initial suggestions for discussion, and are expected to be reviewed by Architect with alterations as necessary. Fissures to elevations west-south 5

6 Fissures to elevations North East Eroded bed joints, voids and generally required conservation works. 6

7 Existing shortened Kingpost. Termination of Kingpost. 7

8 We trust we have covered all your requirements, please do not hesitate to contact us for any queries or clarifications of content. CD enclosed of further digital photographs taken. We attach sample specification for Lime Mortar. General Mortar Specification Do not carry out mortar or pointing where there is a risk of frost, a sample panel is to be prepared for approval. Raking Out and Preparation Carefully rake out to a depth of no less than 40mm using hand tools. No angle grinders to be used. Clean out all materials and dust thoroughly wet with clean water. Mortars Mortar shall be natural hydraulic lime NHL 3.5% St Astier quarry or equivalent. One part hydraulic lime to 2.5 parts sand, sands to be agreed as this will affect finish colour. Mixed with mechanical mixer for no less than 25 minutes. Sands to be clean. Angular, sharp grit blended with soft sand and free from impurities. Grading limits to be to BS EN Pointing & Deep Stemming Completely fill all joints, allowing for deep tamping where necessary where packing is required, galetting using matching small stones building in layers of no more than 100mm per day, finishing flush or very slightly recessed, no smearing. Stiff brush finish to bring to surface aggregates. Pointing Protection Wet sacking until surface hardening occurs and appropriate polythene sheeting under inclement conditions. Grouting to be natural lime product made on site with slacked and thoroughly mixed materials form a pliable consistency to fill cavities during gravity application. Yours sincerely David Stone Managing Director 8

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