A development cost comparison between a multi-storey mass timber and reinforced concrete building in South Africa

Van der Westhuyzen, Stephanus (2020-12)

Thesis (MEng)--Stellenbosch University, 2020.

Thesis

ENGLISH ABSTRACT: A study was conducted investigating the economic viability of a multi-storey mass timber building for South Africa through a development cost comparison. First, the research investigated whether South African plantations can provide sustainable volumes of high-grade (S7, S10) timber for a multi-storey mass timber building market. This was followed by the design of two 8 storey commercial buildings, consisting of a mass timber frame and of a reinforced concrete frame, respectively. A focus group workshop, conducted with industry professionals, assisted in the development of the construction schedules. In the subsequent step, a financial model was used to determine the overall development cost and financial feasibility of the ventures. Finally, a sensitivity analysis was conducted to investigate the effect of certain variables on the overall profitability of the mass timber frame development. The research also served as a case study for the implementation of Building Information Modelling (BIM) in a project team. Through this, an assessment was made regarding the benefits and limitations of BIM. The research revealed that mass timber products would need to be imported to satisfy a rapid growth in the multi-storey mass timber building market in South Africa as current timber supplies (S5, S7, S10) are oversubscribed. Studies suggest that future log resources could be added to the market through the development of new plantations, however, these plantations will only become available after 24 to 30 years. The focus group workshop identified that the construction of the reinforced concrete frame building and mass timber frame building will take 42 weeks and 21 weeks, respectively. The total capital investment required for the mass timber frame development was 10% more than that of the reinforced concrete frame development (R115 691 000 versus R105 118 000). A 5 year internal rate of return (IRR) of 20.9% and 25.7% was calculated for the mass timber frame and reinforced concrete frame developments, respectively. Notably, the 5 year IRR of both developments is above the 15% minimum acceptable rate of return (MARR), indicating that they are both financially feasible. A significant finding of the sensitivity analysis was that the mass timber frame building proved to generate a higher 5 year IRR than that of the reinforced concrete frame once the mass timber building achieved a rental premium of 7.8% or more. The sensitivity analyses further showed that the importation of the mass timber elements remains an expensive option, with a 16.4% 5 year IRR for the imported mass timber frame (R17:€1 exchange rate). The study highlighted a number of aspects, particularly in the manufacturing sector, that can be addressed in order to develop a sustainable multi-storey mass timber building market. This includes improvement in the sourcing of high-grade structural timber (S7, S10) and investment into equipment to enable the large-scale production of large beams/columns typically required in multi-storey mass timber structures. Shortcomings were observed in the all-round implementation of BIM, particularly regarding the information provided by South African suppliers of mass timber elements. Nonetheless, a number of the BIM benefits were realised, with the main advantages being 3D visualisation and clash detection.

AFRIKAANSE OPSOMMING: 'n Studie is uitgevoer om die ekonomiese lewensvatbaarheid van 'n multi-verdieping massahoutgebou vir Suid-Afrika te ondersoek, deur middel van n ontwikkelingskoste benadering. Die volhoubare volumes van hoë-gehalte (S7, S10) hout wat deur Suid-Afrikaanse plantasies gelewer kan word vir multi-verdieping massahoutgeboue, is eerstens ondersoek. Dit is gevolg deur die ontwerp van twee kommersiële geboue van 8 verdiepings elk, bestaande uit 'n massahoutraamgebou en 'n gewapende betonraamgebou, onderskeidelik. 'n Fokusgroep werkswinkel, onderneem met professionele persone in die boubedryf, het gehelp met die ontwikkeling van die konstruksieskedules. In die daaropvolgende stap is 'n finansiële model gebruik om die algehele ontwikkelingskoste en finansiële uitvoerbaarheid van die ondernemings te bepaal. Laastens, is 'n sensitiwiteitsanalise uitgevoer om die effek van bepaalde veranderlikes op die algehele winsgewendheid van die ontwikkeling van die massahoutgebou te ondersoek. Die ondersoek het gedien as 'n gevallestudie vir die implementering van ‘Building Information Modelling’ (BIM) in 'n projek. Die voordele en beperkings van BIM is sodoende bepaal. Daar is gevind dat massahoutprodukte ingevoer sal moet word om 'n vinnige toename in die multi-verdieping massahout mark in Suid-Afrika te bevredig, aangesien die huidige houtvoorraad (S5, S7, S10) onvoldoende is. Die studie bevind dat toekomstige houtbronne tot die mark toegevoeg kan word deur die ontwikkeling van nuwe plantasies, maar hierdie plantasies sal eers na 24 tot 30 jaar beskikbaar word. Die fokusgroep werkswinkel het geïdentifiseer dat die konstruksie van die betonraamgebou en massahoutraam gebou onderskeidelik 42 weke en 21 weke sal duur. Die totale kapitale belegging benodig vir die ontwikkeling van die massahoutraam-ontwikkeling was 10% meer as dié van die gewapende betonraam-ontwikkeling (R115 691 000 teenoor R105 118 000). 'n 5 jaar interne opbrengskoers (IOK) van 20,9% en 25,7% is onderskeidelik bereken vir die massahoutraam- en gewapende betonraam-ontwikkelings. Die 5 jaar IOK van albei ontwikkelings is hoër as die 15% minimum aanvaarbare opbrengskoers (MAOK), wat daarop dui dat albei ontwikkelings finansïeel haalbaar is. 'n Belangrike bevinding van die sensitiwiteitsanalise is dat die massahoutgebou 'n hoër 5 jaar IOK het as dié van die gewapende betonraamgebou indien die massahoutgebou 'n huurpremie van 7,8% of meer behaal het. Die sensitiwiteitsanalise toon verder dat die invoer van massahoutelemente 'n duur opsie bly, met 'n 5 jaar IOK van 16,4% vir die ingevoerde massahoutgebou (R17: € 1 wisselkoers). Die studie het 'n aantal aspekte identifiseer, veral in die vervaardigingsektor, wat aangespreek kan word om 'n volhoubare mark vir massahoutgeboue te ontwikkel. Dit sluit in die verbetering in beskikbaarheid van hoëgraadse struktuurhout (S7, S10) en investering in toerusting wat die grootskaalse produksie van groot balke/kolomme moontlik maak vir multi-verdieping massahoutstrukture. Tekortkominge is waargeneem in die algehele implementering van ‘BIM’ veral met betrekking tot inligting van verskaffers van massahoutelemente. Daar is egter ‘n aantal van die BIM-voordele bevestig, met die belangrikste voordele die 3D-visualisering en identifiseering van botsings tussen elemente/dienste.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/109142
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